The Soy Protein Research Committee(Japan)


11-1

SEPARATION OF GLYCOLIPID IN SOY PROTEIN ISOLATE

Seiichi HOMMA, Tomoko MITA and Masatsune MURATA

Department of Nutrition and Food Science, Ochanomizu University

Nutr. Sci. Soy Protein, Jpn. 11, 7-10, 1990.

Soy protein isolate (SPI) was fractionated by cryoprecipitation after dispersing in water and by isoelectric precipitation after dissolving in alkaline solution. Lipid in the fractions was extracted with 87% ethanol and lipid class was compared by TLC. The TLC profiles for glycolipid slightly differed and those for phospholipid differed significantly by fraction. SPI was extracted with 87% alcohol and chromatographed on a silicic acid column. The yield of lipid from SPI was 2%. The extracted lipid consisted of 10% of neutral lipid, 30% of glycolipid and 60% of phospholipid. Sugars in the glycolipid were mannose (35%), galactose (50%) and glucose (15%). Major fatty acids were palmitic acid (33%), oleic acid (13%) and linoleic acid (28%). TLC revealed that glycolipid consisted of 14 components by alpha-naphthol detection. The glycolipd fraction was emulsified in water by sonification, and fractionated by a ConA-Agarose affinity column chromatography. The spots on TLC and sugar composition differed by the fractions and it suggests that the lectin affinity chromatography is a possible method to fractionate glycolipid.


11-2

STUDIES ON PRODUCTION OF TOFUYO USING SOY PROTEIN ISOLATE ÅF CHANGES IN PHYSICAL PROPERTIES OF THE PRODUCT DURING RIPENING PERIOD

Masaaki YASUDA and Seiji MORIKAWA

College of Agriculture, University of the Ryukyus

Nutr. Sci. Soy Protein, Jpn. 11, 11-16, 1990.

New fabricated tofuyo which is prepared from soy protein isolate (SPI) is a useful model system for a traditional tofuyo, because it is more simple method and easier to produce uniform quality than those of traditional one. Thus, this method was used in order to reveal the ripening mechanisms of tofuyo. In this paper, changes in physical properties of tofuyo during 60-day fermentation, which was prepared by red, yellow, and their mixed kojis, were investigated. The values of hardness, brittleness, gumminess and breaking strength of the product increased for initial 5 days of ripening, but they decreased after 5 days of ripening. Cohesiveness of the products decreased during the ripening period. These physical values of the product prepared by red koji were higher than those of yellow koji. And these values of the product prepared by mixed koji were situated between red and yellow kojis. Creep behavior curves of the product were also investigated. Although compliance of the product prepared by red koji decreased during the ripening period, its value of the product of yellow koji increased during the ripening period. Deformation of the products prepared by red, mixed, and yellow kojis depended upon the elasticity, both elasticity and viscoelasticity, and viscoelasticity, respectively.


11-3

UTILITY OF SOY PROTEIN ISOLATE AND ITS ADMIXTURE AS ANTIOXIDANTS IN PRESERVATION OF HIGHLY UNSATURATED LIPIDS

Fumio IBUKI and Kimikazu IWAMI

Faculty of Agriculture, Kyoto Prefectural University

Nutr. Sci. Soy Protein, Jpn. 11, 17-22, 1990.

Food proteins such as SPI, wheat gliadin and milk casein were examined for their antioxidant effects in powder model systems (37Åé, various Aw's) using a mixture of each protein and its one-ninth amount of safflower oil. The antioxidant effect was evaluated by POV measurement or more correctly by gas-chromatographically determined portions of the constituent linoleic and palmitic acids in safflower oil. SPI was inferior to gliadin in antioxidation at high humidity, and vice versa at low and moderate humidities. Previous de-fat treatment of SPI and gliadin with chloroform-methanol (2 : 1) did not or little affect their antioxidant effects at high humidity. When a 1 : 1 mixture of SPI and gliadin was used to compensate for SPI not so much effective at high humidity as at low humidity, the constituent linoleic acid in safflower oil was kept intact through the experimental period of 6 weeks. It thus seems likely that blending of these food proteins in appropriate portions is effective in improving their individual functional and physical properties more favorably.


11-4

DEVELOPMENTS IN NOVEL FUNCTIONAL FOOD MATERIALS BY HYBRIDIZATION OF SOY PROTEIN TO POLYSACCARIDES

Kunihiko KOBAYASHI, Akio KATO and Naotoshi MATSUDOMI

Faculty of Agriculture, Yamaguchi University

Nutr. Sci. Soy Protein, Jpn. 11, 23-28, 1990.

Acid precipitated soy protein (APP)-dextran (DX) and commercial SPI (FPR)-DX hybrids were prepared by dry-heated storage at 60Åé and 65% relative humidity for 3 weeks. SDS-PAGE patterns showed that APP-DX hybrid obtained by dry heating was much higher molecular weight than APP by stains of proteins and carbohydrates. The average molecular weight of APP-DX hybrid was about 435,000 by low-angle laser light scattering technique and its binding ratio was 1 : 1 (w/w). Solubilities of APP-DX and FPR-DX hybrids increased, especially in acidic pH (4.0), compared with APP and FPR, respectively. Emulsifying properties of APP-DX and FPR-DX hybrids were much more excellent than of APP and FPR, respectively, and were equal to those of commercial emulsifiers. Thus, it is suggested that soy protein-polysaccharide hybridization by controlled dry heating was the available technique for novel functional food materials.


11-5

IMPROVEMENT OF NUTRITIONAL VALUE AND FUNCTIONAL PROPERTIES OF SOYBEAN GLYCININ BY PROTEIN ENGINEERING

Makoto KITO, Jiro KANAMORI and Shigeru UTSUMI

Research Institute for Food Science, Kyoto University

Nutr. Sci. Soy Protein, Jpn. 11, 29-34, 1990.

Glycinin is one of the most predominant storage proteins of soybean. To improve its functional properties (heat-induced gelation and emulsification) and/or nutritional value, the A1aB1b proglycinin subunit was modified on the basis of genetically variable domains suggested from the comparison of amino acid sequences of glycinin-type globulins from various legumes and nonlegumes and the relationships between the structure and the functional properties of glycinin. Thus, nucleotide sequences corresponding to each of the variable domains were deleted from the cDNA encoding the A1aB1b proglycinin, and a synthetic DNA encoding four continuous methionine residues was inserted into the cDNA region corresponding to each of the variable domains. Expression plasmids carrying the modified cDNAs were constructed and expressed in E. coil strain JM105. Some of the modified proteins were accumulated as self-assembled soluble proteins in the cells at a high level. They exhibited functional properties superior to those of the native glycinin from soybean, which indicates the creation of theoretically designed novel glycinins with high food qualities.


11-6

EFFECTS OF DIETARY PROTEIN ON mRNA LEVELS OF LIPOGENIC ENZYME SET IN LIVER

Nobuko IRITANI 1, Naomi NISHIMOTO 1,Hitomi FUKUDA 1,
Akihiko KATSURADA 1,Yohko MATSUMURA 1 and Takehiko TANAKA 2

1 Tezukayama Gakuin College
2 Osaka University Medical School

Nutr. Sci. Soy Protein, Jpn. 11, 35-38, 1990.

To investigate the effects of dietary protein on gene expression for lipogenic enzymes, the mRNA inductions were examined after feeding various protein (fat-free) diets to fasted rats. By feeding a carbohydrate diet (without protein), the transcriptional rate, mRNA concentration and enzyme induction of acetyl-CoA carboxylase were similarly increased to the levels in the carbohydrate/protein diet. It appears that protein-feeding is not necessary to induce acetyl-CoA carboxylase. In the animals the transcriptional rates and mRNA concentration of malic enzyme were increased to the levels in the carbohydrate/protein diet, whereas the enzyme induction was increased only to 60%. Protein appears to contribute to an increase in the translation of malic enzyme. Both carbohydrate and protein were required to induce fatty acid synthase and glucose-6-phosphate dehydrogenase, primarily at the transcription. The mRNA inductions of these enzymes were significantly lower in the zein and gluten groups than in the casein group. Supplement of lysine and tryptophan to zein, the mRNA inductions were significantly increased. Thus, it may be possible that Lys and Trp are involved in fatty acid synthase and glucose-6-phosphate dehydrogenase inductions before the translation.


11-7

EFFECT OF DIETARY SOY PROTEIN ON BODY FAT Ming-Fu WANG, Sheng-Chi HUANG and Hei-Mei CHUNG

Department of Food and Nutrition, Providence University (Taichung Taiwan)
Tomoo KOHRIN and Masahiro MORI
Department of Domesitic Science, Kinran Jonior College
Sumie SHINJO, Lyu ASATO and Shigeru YAMAMOTO
Faculty of Medicine, University of the Ryukyus

Nutr. Sci. Soy Protein, Jpn. 11, 39-42, 1990.

Effects of the kind of dietary proteins on body fat were studied in rats and women. In the first experiment, adult rats were given the isoenergetic amount of soy protein diet or casein diet for 9 weeks. Accumulation of body protein and fat was higher in the casein diet group than in the soy protein diet group. In the second and third experiments, obese rats or women were given the isoenergetic and restricted amount of soy protein or milk protein diet for 21 days. In the both experiments, decrease of body fat was greater in the soy protein diet group than in the milk protein diet group. The results of the three experiments indicate that the effect of the kind of proteins on the body fat is different.


11-8

METABOLIC FATES OF CARBON SKELETONS OF AMINO ACIDS IN GROWING RATS FED THE SOY PROTEIN ISOLATE DIETSÅF LEUCINE, LYSINE, SERINE AND ALANINE

Hideyuki TANAKA and Masaji OGURA

Faculty of Agriculture, Utsunomiya University

Nutr. Sci. Soy Protein, Jpn. 11, 43-48,1990.

The metabolic responses of carbon skeleton of individual amino acid to dietary protein intake have investigated in growing rats fed the diets containing graded levels (5, 10, 15, 20, 30 or 40 protein calories %; PC%) of the soy protein isolate "Fuji-pro R" at 4,100 kcal of metabolizable energy per kg of diet. Body weight gain reached approximately a plateau at 20 PC% in the diet. At 12 hr after the intraperitoneal injection of L-[U-14C] leucine, L-[U-14C] lysine, L-[U-14C] serine and L-[U-14C] alanine, the distribution of the radioactivity in expired carbon dioxide, urine, body protein, lipid and soluble fractions was measured. The overall oxidative degradation of the essential amino acids, leucine and lysine, was depressed in the protein depletion, but it increased gradually at higher PC% in the diet. The incorporation of 14C into the body protein from labeled leucine and lysine was high in protein depletion but it declined in the higher PC% groups. The carbon skeleton of serine was nonspecifically incorporated into the body protein, and alanine was oxidized to a great extent over the all range of dietary protein levels. These results suggest that the carbon skeletons of essential amino acids (methionine, threonine, leucine and lysine) are preferentially utilized for protein synthesis, and that the metabolic responses of these amino acids to dietary protein intake change at around 20 PC%, where the growth rate reached its maximum.


11-9

EFFECT OF ENERGY RESTRICTION ON NITROGEN BALANCE IN YOUNG WOMEN FED A CONVENTIONAL LOW PROTEIN DIET CONTAINING SOY PROTEIN ISOLATE

Kayoko KANEKO 1,Goro KOIKE 2 and Mituyo AIKYO 2

1 Faculty of Education, Yokohama National University
2 Kagawa Nutrition College

Nutr. Sci. Soy Protein, Jpn. 11, 49-54, 1990.

Effects of energy restriction and aerobic exercise on nitrogen (N) balance were studied in non-obese eleven female students aged 19 to 23 years old. Six of them were fed in order two experimental diets containing 120 and 200 mg/kg/day of N with low energy as 1.1 times of basal metabolism (BM) for 10 days each. Other five subjects performed aerobic exercise (jogging and ergometer exercise) of about 200 kcal/day in two 10-day experimental periods during which they received diets containing 85 and 115 mg/kg/day of N with low energy (1.25 times of BM). Calculated energy balance was about -200 to -300 kcal/day and there was no significant difference between two groups. Means of weight loss during 10 day experimental periods were 0.3 to 1.2 kg, not significantly different between two groups or N intake levels in a group. N balances were negative in both groups at two levels of N intake. In the only energy restricted group, no improvement was obtained in negative N balance when N intake increased from 120 to 200 mg/kg/day. In the exercised group with energy restriction, nitrogen balance improved when intake N increased, a significant regression equation between N intake (x) and N balance (y) was obtained and the figure of 127.5 mg N/kg/day as intersection of regression line with zero balance was obtained. It is suggested that protein requirement increases significantly when low energy diet is used for the prevention of obesity in non-obese people and aerobic exercise diminishes the increment.


11-10

EFFECTS OF LONG - TERM FEEDING OF SOY PROTEIN ISOLATE ON PROTEINURIA AND AGE - RELATED CHANGES IN SOME PHYSIOLOGICAL VARIABLES IN ADULT RATS UNDER RESTRICTED FEEDING CONDITION

Hidemichi EBISAWA, Mineko ICHIKAWA, Tomoko OZEKI and Yoshiaki FUJITA

Nutrition Research Laboratory, Tokyo Metropolitan Institute of Gerontology

Nutr. Sci. Soy Protein, Jpn. 11, 55-59,1990.

Effect of long-term feeding of soy protein isolate (SPI) on urinary protein excretion and age-related changes in some physiological variables was examined in adult rats under restricted feeding condition. Four-month-old, male Wistar rats were divided into two groups of 12 rats each. Groups CR and SR received 10 g/day of 20% casein diet and 20% SPI diet, respectively, until 800 days of age. Results are as follows: 1) As compared with casein, SPI had less incidences in histologic lesions in the liver and kidney. 2) SPI was nutritionally comparable to casein in criteria of nitrogen balance, serum albumin, and protein excretion in the urine. 3) Results of free amino acids in serum showed that in long-term feeding of SPI, methionine supplementation to diet may result in some beneficial affections. 4) Hypocholesterolemic effect of SPI was also observed in a long-term feeding of SPI under restricted feeding conditions.


11-11

BASIC STUDIES ON SOYBEAN - ASSOCIATED ALLERGY

Soichi ARAI 1 and Hiroko KIMURA 2

1 Faculty of Agriculture, The University of Tokyo
2 Kagawa Nutrition College

Nutr. Sci. Soy Protein, Jpn. 11, 60-62, 1990.

An acid-precipitated protein constituted mainly with 7S and 11S fractions was prepared from raw soybeans after defatting with ethyl ether. A similar protein was prepared from soy protein isolate (SPI). Each of the proteins was investigated for immunogenicity by using guinea pigs. It was found that the protein from raw soybeans showed an appreciable degree of immunogenicity, which was caused primarily by its 7S fraction. This acid-precipitated protein containing the 7S fraction was treated at 65Åé for 180 min or at 80Åé for 90 min, but its immunogenicity did not decrease. However, when the protein treated at 80Åé for 90 min was hydrolyzed with trypsin, the resulting product showed no immunogenicity. These results suggest that in raw soybeans a certain heat-stable component exists, which may possibly induce allergy and also that enzymatic hydrolysis following heat treatment could be effective in producing a hypoallergenic soybean protein hydrolysate.


11-12

HYPOCHOLESTEROLEMIC EFFECT OF SOYBEAN PROTEIN IN RATSÅF INTERACTION OF DIETARY FAT AND AGE

Yong-Soon CHOI, Ikuo IKEDA and Michihiro SUGANO

Faculty of Agriculture, Kyushu University

Nutr. Sci. Soy Protein, Jpn. 11, 63-66, 1990.

The hypocholesterolemic effect of soybean protein (SOY) was compared with casein (CAS) and milk whey protein (WHY) in 4 weeks and 9 months old rats using sardine oil as the source of dietary fat. The protein effect was more evident in liver cholesterol (CHOL) than in serum CHOL and in old than in young rats. SOY increased fecal steroid excretion and the CHOL synthesis in the liver. Significant age- and protein-effects were observed in fatty acid profiles of liver microsomal phospholipid. Thus, the effects of soybean protein on various lipid indices are routinely maintained even when fish oil was fed simultaneously.


11-13

NUTRITIONAL SPECIFICITY OF SOY PROTEIN ISOLATE FOR SERUM LIPOPROTEIN METABOLISM IN RATS

Hiroaki ODA, Shin-ichi NIWA and Akira YOSHIDA

School of Agriculture, Nagoya University

Nutr. Sci. Soy Protein, Jpn. 11, 67-73, 1990.

We previously demonstrated that soy protein has a hypocholesterolemic effect in rats as compared with either casein or rice protein although fecal excretion of steroids was stimulated by soy protein and rice protein. We also reported that the hypocholesterolemic effect of soy protein appeared after one day of feeding soy protein, and secretion rate of very low density lipoprotein (VLDL) was concomitantly repressed by soy protein. These results suggest the importance of alterations in the secretion of lipoproteins and in the synthesis of apolipoproteins. In this paper, distribution of lipids and apolipoproteins among lipoproteins was investigated in detail. Serum level of cholesterol in rats fed soy protein was lower than that in rats fed casein or rice protein after one day feeding of the experimental diets and kept the lower value on day 7. High density lipoprotein (HDL) cholesterol contributed to the lowered level of cholesterol due to soy protein. However, on day 1 serum level of apolipoprotein A-I (apo A-I) which is a major apolipoprotein in HDL was not significantly lower in rats fed soy protein as compared with casein or rice protein groups and was reduced by soy protein on day 7. From the results of ultracentrifugation separation of serum lipoproteins, soy protein suppressed the level of apo E-rich lipoproteins, HDL1 and VLDL, at early period of feeding soy protein and subsequently soy protein reduced the level of apo A- I rich lipoprotein, HDL2. Since hepatic level of apo A-I mRNA was lower in rats fed soy protein as compared with casein or rice protein on day 1, this reduction of apo A-I mRNA might be responsible for the suppression of the serum level of HDL cholesterol due to soy protein on day 7.


11-14

SPECIES DIFFERENCE IN THE EFFECT OF DIETARY PROTEINS ON STEROID EXCRETION

Shin-ichi HAYASHI, Miwako KAMIMURA, Mariko NAITO,
Junko YAMASHITA and Koichi YAMAZAKI

Department of Nutrition, The Jikei University School of Medicine

Nutr. Sci. Soy Protein, Jpn. 11, 74-77, 1990.

Rate of fecal steroid excretion was determined in rats and mice by infusing [4-14C)] cholesterol into stomach and then measuring radioactivity in total, neutral and acidic steroids extracted from feces collected for up to 4 days after infusion. In male Sprague-Dawley rats feeding casein diet for 3 weeks caused an increase in plasma cholesterol level and a decrease in the rate of fecal steroid excretion compared with SPI diet. On the contrary, in both male and female ICR mice feeding casein or SPI diet resulted in similar plasma cholesterol level and similar rate of fecal steroid excretion. Thus, as far as the effects of dietary proteins concerned, there was a good correlation between their effects on lowering plasma cholesterol level and on stimulating fecal steroid excretion, suggesting that the hypocholesterolemic effect of soy protein observed in various animals including rabbits, pigs and rats is due to its effect to stimulate fecal steroid excretion.


11-15

NUTRITIONAL EVALUATION OF DIETARY PROTEIN, PEPTIDES, AND AMINO ACIDS USING OLIGOMETHIONINE AS A PROBE FOR EXOCRINE PANCREATIC SECRETION

Shuhachi KIRIYAMA 1,Xiaohong YIN 1 and Hideyuki CHIJI 2

1 Faculty of Agriculture, Hokkaido University
2 Fuji WomenÅLs College

Nutr. Sci. Soy Protein, Jpn. 11, 78-82, 1990.

When oligo-L-methionine (OM, a mixture of hexa- and hepta-methionine) was supplemented to low casein (Cas) and soybean protein isolate (SPI) diets, growth-stimulating effects of OM was observed only in the Cas diet. In this report, following experiments were made to clarify the cause of the difference in effects of feeding OM-supplemented Cas or SPI diets. Dietary nitrogen sources used here were SPI, its pepsin hydrolysate (molecular weight :1.5Å`10 kD, SPI-H), insoluble residues after pepsin hydrolysis of SPI (SPI-R), a mixture of small peptides from SPI (containing di- and tri-peptides and amino acids supplied by Fuji Oil Co., SPI-SP), and the corresponding amino acid mixture (SPI-AA). In experiment 1, we compared the digestibility of OM by measuring the incremental portal methionine (Met) concentration (delta-PMC) 30 min after feeding diets containing above nitrogen sources with 3% OM to fasted rats. Delta-PMC of rats fed SPI-H plus 3% OM diet was two times higher than that when fed the SPI plus 3% OM diet. In experiment 2, rats were fed the same diets supplemented with 0.3% Met or 0.3% OM for 2 wk to compare the supplemental effects of Met and OM. The addition of 0.3% OM to SPI-H and SPI-AA diets significantly improved the growth rate of rats. When 0.3% OM was supplemented to SPI, SPI-R, and SPI-SP diets, the growth rate was not improved. There was a close correlation between delta-PMC and growth-stimulating effects of OM supplemented to diets containing nitrogen sources with various molecular sizes (r=0.97, n=4, pÅÉ0.01), except for the case of SPI-SP. These results suggest that nitrogen sources used here have different abilities to stimulate exocrine pancreatic enzyme secretion (SPI-H has the highest).


11-16

EVALUATION OF NUTRITIVE VALUE OF PEPTIDE PREPARATIONS DERIVED FROM SPI

Tadashi NOGUCHI, Jong Hee KIM and Yutaka MIURA

Faculty of Agriculture, The University of Tokyo

Nutr. Sci. Soy Protein, Jpn. 11, 83-86, 1990.

Nutritive value of peptide preparations (Hinute PM and S) derived from SPI was determined by two recently developed methods: response of plasma immunoreactive and total insulin-like growth factor I (IGF-I) concentrations and urinary excretion of acid soluble peptides (ASP). Plasma immunoreactive IGF-I concentration was significantly lower in the rats fed on the Hinute PM or S diet than in those fed on a casein diet. Plasma immunoreactive IGF-I / total IGF-I ratio was also lower in the rats fed on the Hinute PM or S diet than in those given the casein diet. These results suggest that the activity of protein anabolism is lower in the Hinute-fed rats than in the casein-fed rats. Supplementation of methionine to the Hinute diets improved the nutritive value significantly. There was no significant difference between the Hinute-fed rats and casein-fed rats in the urinary excretion of ASP. This suggests that the rate of whole body protein degradation is not significantly different between the Hinute-fed and casein-fed rats. These results suggest that the difference in the growth rate in the rats given the Hinute and casein diets is due to the difference in the rate of whole body protein synthesis.


11-17

EFFECTS OF SOY PROTEIN PEPTIDE ON NUTRITIONAL STATE AND SMALL INTESTINAL FUNCTION IN SHORT-BOWEL AND METHOTREXATE TREATED RATS

Mika IHARA, Tomoko MIYANOMAE, Yasuhiro KIDO and Kyoichi KISHI

Department of Nutrition, School of Medicine, The University of Tokushima

Nutr. Sci. Soy Protein, Jpn. 11, 87-94, 1990.

The effects of different forms of nitrogen source on nutritional state and small
intestinal function were investigated in rats with short-bowel (Exp.1) and inje
cted with methotrexate (MTX) (Exp. 2). In Exp. 1, 80% small intestine resected rats (SB group) and control sham-operated rats (C group) were both fed ad libitum 10% (N Å~ 6.25) diets containing soy protein isolate (SPI), soy protein peptide (SPP) or amino acid mixture (SAA) simulating soy protein peptide for 13 days. As a result, body weight gain was greatest in SPP diet of both C and SB groups. The post-operative recovery period of SB group was shorter for SPI and SPP diets than SAA diet. Protein efficiency ratio (PER) tended to be better for SPP diet in SB group especially at the beginning of the recovery period. This tendency was also observed for mucosal weight, protein content and diamine oxidase (DAO) activity of the small intestine. From these results, it is concluded that in short-bowel rats when the small intestine is normal or relatively in good condition, there is no difference of nutritional effect among intact protein, peptides and amino acid mixture, but immediately after the operation, peptides seemed to be more effective than protein or amino acid mixture. In Exp. 2, MTX (0.2 mg/kg/day) was injected intraperitoneally for 14 days to rats receiving either 10% SPI, SPP, SAA or casein diet (M group). For control (C) group, saline was injected. PER of M group was highest for SAA diet, followed by SPP and SPI diets, whereas nitrogen balance was slightly higher for SPP diet than for other dietary groups. Differences in body weight, small intestinal mucosal weight and protein content were not observed between C and M groups. As a conclusion, in MTX injected rats, peptide or amino acid seemed to be better utilized than the intact protein. However, in the present experiment, since the intestinal damage caused by MTX seemed to be too light, in order to confirm the suitability of peptides for enteral source of nitrogen in the gastrointestinal disturbances, further studies are required employing other experimental designs or models.


11-18

EFFECTS OF SOY PROTEIN PEPTIDES ON SYMPATHETIC NERVE ACTIVITY

Masayuki SAITO

Faculty of Veterinary Medicine, Hokkaido University

Nutr. Sci. Soy Protein, Jpn. 11, 95-97, 1990.

Effects of dietary soy protein peptides on sympathetic nerve activity were examined in rats. Groups of female Wistar rats (130Å`140 g) were given a diet containing either soy protein peptides (SP) or amino acids (ED) for 10 days. To assess sympathetic nerve activity in individual peripheral organs, norepinephrine (NE) turnover rate was calculated from the decline of organ NE content after blocking NE biosynthesis with Éø-methyl-p-tyrosine. NE turnover in the liver was much less in SP group (0.2 ng/g/h) than ED group (1.2 ng/g/h). On the other hand, NE turnover in the interscapular brown adipose tissue, a specific site for sympathetically controlled thermogenesis, was increased in SP group, suggesting an activation of thermogenesis in this organ. These results are quite consistent with our previous findings that SP diet elicited an increase in GDP-binding to brown fat mitochondria, another index of thermogenesis, and that whole body energy expenditure was higher under SP diet.


11-19

COMPARISON BETWEEN EFFECTS OF ENERGY RESTRICTED DIETS SUPPLEMENTED WITH SOYBEAN PEPTIDE AND LACTALBUMIN ON ENERGY, PROTEIN AND LIPID METABOLISMS IN TREATMENT OF OBESE CHILDREN

Tatsushi KOMATSU 1,Keiko KOMATSU 2,Mie MATSUO 2,Masato NAGATA 3 and Minoru YAMAGISHI 4

1 Unit of Nutrition in Hospital, University of Occupational and Environmental Health
2 Fukuoka Junior College of Social Work and Child Education
3 Nagata Hospital
4 Department of Pediatrics, University of Occupational and Environmental Health

Nutr. Sci. Soy Protein, Jpn. 11, 98-103, 1990.

A study was conducted to compare the effects of soypeptide (SPT) and lactalbumin (LA) supplement to energy restricted 1000 kcal diets on energy, protein and lipid metabolisms in 5 obese children aged 5Å`16 yr. Obesity degrees were 35Å`81% over their ideal body weight. Following a standard period for 3 days, two test diet periods for 8 days were set up. During the two test meal periods, patients were given 30g of SPT and/or LA alternately or continuously as a protein supplement food. The body weight loss during hospitalization was 2.8 Å} 0.8 kg. Mean changes in basal metabolism during SPT and LA supplemented periods were + 2.3 kcal/hr and - 4.8 kcal/hr, respectively. There was a significant difference between the two values. Mean N balances maintained at approximately zero in the last 3 days of both N source periods. But serum proteins (total protein, retinol binding protein and prealbumin) decreased during test meal periods, suggesting that nutritional status was slightly affected. Though total cholesterol in serum decreased, HDL-cholesterol did not decrease much. As a result, an atherogenic index (AI) improved in all patients. AI of SPT supplemented subjects was lower than that of LA supplemented one in the 2nd half of two periods.


11-20

UTILIZATION OF SPI HYDROLYZATE (SPT-5) FOR ENTERAL AND PARENTERAL NUTRITION

Yoshiaki NIIYAMA and Sachinobu MANABE

Department of Nutrition, School of Medicine, The University of Tokushima

Nutr. Sci. Soy Protein, Jpn. 11, 104-107, 1990.

Changes in levels of free and peptide form amino acids in serum were investigated in SPT-5 fed rats. In preliminary experiment, effects of various concentrations of sulfosalicylic acid (SSA) on free amino acids and average peptide chain length in deproteinized serum were examined. As a result, addition of 3.3% or more SSA (final concentration) to serum was suitable for detecting the constant values of free amino acids and endogenous small oligopeptides. If lower than 3.3% SSA was used for deproteinization, larger oligopeptides remained in deproteinized serum. Sprague-Dawley young adult rats were meal-fed 20% SPT-5 diet during 10:00Å`12:00. Changes in serum free and peptide form amino acids were investigated after feeding. Free amino acid concentration increased immediately after feeding and then decreased to fasting level. No changes in peptide form amino acids were observed after feeding, showing that a large amount of oligopeptides entered into blood stream as free amino acid form.


11-21

NUTRITIONAL EVALUATION OF OLIGOPEPTIDE MIXTURE, PREPARED FROM SOY PROTEIN ISOLATE(SPI) IN RATS RESECTED TWO - THIRDS OF THE SMALL INTESTINE

Yukihiro NAKABOU, Takeshi SUZUKI, Miyuki OKAMOTO,
Yuuko KUZUHARA and Hiroshi HAGIHIRA

Department of Nutrition, School of Medicine, The University of Tokushima

Nutr. Sci. Soy Protein, Jpn. 11, 108-112, 1990.

Nutritional evaluation of a chemically defined balanced diet (PM-S) containing oligopeptide (mean chain length, 2.1), prepared from soy protein isolate (SPI) supplemented with L-Met, as a nitrogen source was studied in rats resected two-thirds of the small intestine. After the operation, the animals were given intraduodenally one of the following diets; PM-S, ELENTAL and ENTERUED for 10 days. The results were summanized as followsÅF (1) no differences in body weight gain and nitrogen balance were observed among three diets, (2) protein efficiency ratio and nitrogen balance index were somewhat lower in PM-S, than in ENTERUED, (3) no appreciable differences in DNA content and brush border hydrolase activities of the small intestine were found in three groups, (4) concentration of plasma triglyceride in all groups was extremely lower than in unoperated control group. These findings suggest that oligopeptides prepared from SPI can be used as a good nitrogen source for enteral nutrition.


11-22

EFFECT OF PEPTIDES ON BRUSH BORDER TRANSPORTERS IN RAT INTESTINE AND CLINICAL USEFULNESS OF SOY PEPTIDES IN THE PATIENTS WITH MALABSORPTION SYNDROME

Tadao BAMBA, Hirozumi OBATA, Masako NISHIMURA, Tomonori HOSODA,
Nobuo CHIKAMOCHI and Shiro HOSONO

Second Department of Internal Medicine, Shiga University of Medical Science

Nutr. Sci. Soy Protein, Jpn. 11, 113-119, 1990.

In the previous study, we have reported that the number of amino acid and peptide transporters in the rat intestine significantly increased after the administration of peptides as intraluminal substrates. Present study was undertaken to reconfirm the previous results and to clarify the dipeptide intact absorption, by rapid filtration method using brush border membrane vesicles (BBMV). Male Wistar rats were fed amino acid mixture (AA) or small peptides (SP) isocalorically for 4 weeks. BBMV were obtained according to Kessler's method. L-14C-leucine uptake into BBMV obtained from the intestine of rats fed SP showed an overshoot and significantly increased under Na+ gradient, compared with that of rats fed AA. L-14C-leucylglycine uptake was also increased in the SP rat intestine, in spite of showing no overshoot. However, D-14C-glucose uptake was similar between SP and AA rat intestines. In kinetic parameters of those, Jmax values of L-leucine and L-leucylglycine were significantly increased in the SP rat intestine, but Kt values were almost same. On the other hand, Jmax and Kt values of D-14C-glucose were not different between SP and AA rat intestines. Therefore, these results indicated that amino acid and peptide transporters were significantly increased by the intraluminal peptides. Secondly, the effect of soy peptides in the patients with malabsorption syndrome was examined. Total energy was about 2,000 kcal/day, containing about 90g of protein including about 70g of soy peptides, 20g of fat and 300g of carbohydrate. Serum protein, albumin and rapid turnover protein were increased after 4-week soy peptide treatment. Soy peptides were effective to manage the patients with malabsorption syndrome, especially pancreatic insufficiency.


11-23

STUDY ON SOY PROTEIN DIETS FOR THE CIRRHOTIC PATIENTS

Masahiko KATO, Takashi YOSHIDA, Hisataka MORIWAKI and Yasutoshi MUTO

School of Medicine, Gifu University

Nutr. Sci. Soy Protein, Jpn. 11, 120-124, 1990.

There is a growing body of observations that administration of soy protein is useful as a basal diet for cirrhotic patients with protein-intolerant state. The present study was conducted to determine the most appropriate compositional ratio of soy protein and animal protein in a diet for cirrhotic patients. Six cirrhotic patients were divided into three groups, each of which received one of 3 different kinds of test diets for 4 weeks. All diets provided 2000 kcal energy and 70g protein/day, and compositional ratio of protein was 50% soy protein-free vegetable protein : 50% animal protein in group I, 50% vegetable protein : 25% soy protein : 25% animal protein in group II, and 50% vegetable protein : 50% soy protein in group III. Physical status, liver function tests, serum levels of total protein, albumin and rapid turnover protein, as well as plasma free amino acid, BCAA, AAA and Fischer's ratio and ammonia levels were monitored before and at 1, 2, 3 and 4 weeks of administration. Although patients ingested more than 90% of test diets in every group, those in group III complained that the 100% vegetable diet was "monotonous" and felt a difficulty taking the test diet for the entire observation period. In contrast, those in groups I and II could ingest their test diets easily. No significant changes were observed in physical status or laboratory data in either group during the study. Hence, the compositional ratio of group II was suggested as the most appropriate one, being based on its excellent compliance and the beneficial effect of the soy protein itself.


11-24

EFFECTS OF SOY PROTEIN DIET ON LIPID METABOLISM IN PATIENTS WITH HYPERLIPIDEMIA AND WITH ISCHEMIC HEART DISEASE

Hiromitsu TAMACHI 1, Yuichi FUSEGAWA 1,Yuichiro GOTO 1,Honami FUJII 2,Hiroaki ISHII 2 and Emilio MORIGUCHI 3

1 School of Medicine, Tokai University
2 Unit of Nutrition in Hospital, Tokai University
3 Institute of Geriatrics, Pontifical-Catholic University

Nutr. Sci. Soy Protein, Jpn. 11, 125-130, 1990.

The effects of partial substituting soy protein isolate for dietary animal protein on lipid metabolism were investigated in 8 patients with hyperlipidemia and 3 healthy volunteers. Twenty g/day of soy protein isolate substitution for two weeks lowered levels of serum cholesterol (Å|10%), Phos-L (Å|5.4%), LDL-C (Å|13%), Apoprotein B (Å|13%) and Apo B/Apo A-I ratio (Å|15%) significantly. However, most of subjects pointed out the difficulties to take this diet for more longer time, suggesting the necessity to modify the diet from the clinical point of view.


11-25

EFFECT OF SOYPROTEIN ON PLASMA LIPOPROTEIN LIPIDS, APOPROTEINS AND LIPID TRANSFER PROTEIN ACTIVITY IN THE TYPE IV HYPERLIPIDEMIC SUBJECTS

Haruo NAKAMURA, Emiko MIYAJIMA, Masato NISHIWAKI,
Katsunori IKEWAKI and Kazuo KONDO

National Defense Medical College

Nutr. Sci. Soy Protein, Jpn. 11, 131-133, 1990.

Five mildly hypertriglyceridemic subjects (E3 / E3, 3 ; E4 / -, 2) were subjected to receive 20g soyprotein per day on isocaloric basis for 4 weeks to analyze lipoprotein lipids, apoproteins and lipid transfer activity and the results were compared with those obtained from ten normolipidemic subjects (E3 / E3, 8 ; E4 / -, 2). Plasma triglyceride, cholesterol and phospholipids decreased and apo B decreased, while apo A-I and A-IV remained unchanged. HDL3-cholesterol increased significantly and this was reflected by the reduction of lipid transfer protein activity. HDL2-cholesterol remained unaltered. These results may indicate that soy protein ingestion would be beneficial to halt the progression of atherosclerosis.


11-26

EFFECT OF SOYBEAN TRYPSIN INHIBITOR ON PANCREATIC LESION IN WBN/Kob RATS ÅFCOMPARISON WITH THE EFFECT OF SYNTHETIC TRYPSIN INHIBITOR

Yoshio IKEDA, Yutaka MORI and Junichi YOKOYAMA

Third Department of Internal Medicine, The Jikei University School of Medicine

Nutr. Sci. Soy Protein, Jpn. 11, 134-137, 1990

We previously reported the preventive effect of the synthetic trypsin inhibitor, camostat mesilate, on pancreatic fibrosis in WBN/Kob rats. In the present study, we examined the effect of soybean trypsin inhibitor (SBTI) on pancreatic lesion in WBN/Kob rats and compared with the effect of camostat mesilate. The preventive effect on 1 month-old male rats without pancreatic lesion was examined during a 20-month period (from 1 to 21 months of age). Male WBN/Kob rats were divided into three groups which were fed with the diets containing 2.0% (= 613 U/kg/day), 0.5% (= 153 U/kg/day), or no (= 20 U/kg/day) SBTI. There was no significant difference in incidence of glycosuria, serum amylase activity, and urinary excretion of amylase between the groups. The weight of pancreata and tissue contents of trypsinogen and chymotrypsinogen in pancreata of rats treated with SBTI for 20 months were significantly increased compared with those in non-treated rats. Histologically, pancreata of non-treated rats revealed that the pancreas was atrophic and replaced by fibrous tissue or fat in extensive area. In pancreata of SBTI-treated rats, although the exocrine tissue was hypertrophic, the fibrous area with deposition of hemosiderin, and deformity and decreased number of islets were observed. We conclude that oral administration of SBTI has the trophic effect on exocrine tissue but no preventive effect on the development of pancreatic fibrosis in male WBN/Kob rats.


The soy protein protein reserch(Japan)