The Soy Protein Research Committee(Japan)


15-1

EXPRESSION AND ACCUMULATION OF SOYBEAN GLYCININS MODIFIED BY PROTEIN ENGINEERING IN HIGHER PLANTS

Shigeru UTSUMI

Research Institute for Food Science, Kyoto University

Rep. Soy Protein Res. Com., Jpn. 15, 1-6, 1994.

Chimeric genes composed of A1aB1b preproglycinin cDNA and its modified versions (IV + 4Met and V + 4Met), nopaline synthase gene terminator and the cauliflower mosaic virus 35S promoter or the class I patatin promoter were inserted into the genome of tobacco or potato, respectively by Agrobacterium-mediated transformation. Both normal and modified glycinins accumulated in the leaves, stems and seeds of transgenic tobacco, and no differences in the level of accumulation were observed among the expressed proteins in leaves and seeds. The proteins expressed in each tissue were processed to the mature form, and those expressed in the seeds assembled into hexamers. Translational products in the tubers were observed in parenchyma cells of potato plants transformed with the normal and modified glycinin cDNAs. This distribution is consistent with the expression specificity of the patatin promoter. The expression levels of the normal and the modified glycinins were 0.2Å`1.0% of the total soluble tuber proteins. Both the normal and the modified glycinins expressed in the tubers were present as proglycinin trimers. These results indicate that the modifications in IV + 4Met and V + 4Met did not disrupt any stage in the biosynthetic process of glycinin in tobacco seeds and potato tubers, supporting the possibility that we can create novel soybean plants which can produce modified glycinins having better nutritional and functional properties.


15-2

EFFECTS OF THE LENGTH OF POLYSACCHARIDE CHAINS ON THE IMPROVEMENT OF THE FUNCTIONAL PROPERTIES OF SOY PROTEIN MODIFIED WITH POLYSACCHARIDES

Akio KATO, Yukiyo KIHARA and Shigehiro SAHARA

Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University

Rep. Soy Protein Res. Com., Jpn. 15, 7-12, 1994.

Soy protein was covalently attached to various kinds and sizes of polysaccharides in a controlled dry state (60Åé, 79% relative humidity) through Maillard reaction between the É&Mac195;-amino groups in protein and the reducing-end carbonyl residue in polysaccharide. The length of polysaccharide chains in Maillard-type soy protein-polysaccharide conjugates greatly affected the emulsifying properties, regardless of the kinds of polysaccharides. The larger the length of polysaccharide chains, the greater the increases in the emulsifying properties of protein-polysaccharide conjugates. Among the polysaccharides used in the experiment, dextran and xyloglycan having the molecular weight of 200Å`300 kDa and 470 kDa, respectively, were most remarkably improved the emulsifying properties of protein-polysaccharide conjugates. The importance of the length of polysaccharide chains in the emulsifying properties of protein-polysaccharide conjugates was further proved by using polymannosyl and oligomannosyl lysozymes constructed by genetic engineering.


15-3

DIFFUSION COEFFICIENT OF SEASONINGS IN SOYBEAN PROTEIN GELS AND NETWORK STRUCTURE OF SOYBEAN PROTEIN GELS

Katsuyoshi NISHINARI and Tomohisa TAKAYA

Faculty of Human Life Science, Osaka City University

Rep. Soy Protein Res. Com., Jpn. 15, 13-16, 1994.

An apparatus which permits to determine the diffusion coefficient of seasonings in soybean protein gels was devised. Two chambers of about 300 mL were separated by a gel of disk shape (20 mmÉ”Å~1 or 2 mm thickness). At time t = 0, one chamber is filled with salt solution and the other is filled with distilled water. The value of D was determined based on the concentration change at longer time scale. Diffusion coefficient (D) of sodium chloride in soy protein isolate (SPI)-curdlan gels was determined. The value of D was found to decrease with increasing SPI or curdlan concentration indicating that network density of gels became denser. The correlation between the change in D with increasing concentration of SPI or curdlan and the change in rupture properties or Young's modulus of gels was also examined.


15-4

ROLE OF 7S AND 11S GLOBULINS IN TEXTURAL PROPERTIES OF SOY PROTEIN GEL

Tomohiko MORI

Research Institute for Food Science, Kyoto University

Rep. Soy Protein Res. Com., Jpn. 15, 17-21. 1994.

Heat-set gels were prepared from 7S globulin, 11S globulin, and acid-precipitated proteins of soybeans at various heating temperatures (80Å`100Åé) and at 19% protein concentration. The gels were evaluated for mechanical parameters by means of a compression-decompression test. The onset of gelation coincided with the onset temperature of denaturation in 7S and 11S globulins. In acid-precipitated proteins, the onset of gelation was above the denaturation temperature of 7S globulin but below that of 11S globulin. The 7S/11S ratio affected the mechanical properties of the gels. The 11S globulin exhibited a large effect to make gels hard, tough and unfracturable. The 7S globulin showed significant contribution to gel elasticity. The changes of elasticity of the gels from the acid-precipitated proteins by the heating temperature were different from those of 7S and 11S globulins. This suggested that some interactions between the subunits of 7S and 11S globulins occurred in the case of the acid precipitated proteins. Such interactions may play an important role for mechanical properties of the gels in a mixed system of 7S and 11S globulins such as soy protein isolates. Textural properties of the gels were evaluated by three-dimensional representation of the gels through factor analysis of instrumental data. The results indicated that texture of soy protein gels may be either controlled or changed by means of 7S/11S ratio and heating temperature.


15-5

ISOLATION AND UTILIZATION OF THE PROTEIN FROM ÅgOKARAÅh

Fumio YAMAUCHI 1, Jiun-Rong CHEN 1, Kouji MURAMOTO 1, Setsuko IWABUCHI 1,itsuo ASANO 1 and Kunio SUETSUNA 2

1 Faculty of Agriculture, Tohoku University
2 Shimonoseki University of Fisheries

Rep. Soy Protein Res. Com., Jpn. 15, 22-27, 1994.

Okara that is the waste produced from tofu plant contains 4.7% protein fractions per wet base. The okara proteins were fractionated into water-extractable proteins and water-insoluble proteins. After removal of water-soluble proteins (soy milk), the residue was extracted with various solvents; NaCl, urea, and SDS solutions. SDS gel electrophoretic analysis revealed that 0.3 M NaCl extracts composed of a single band of 42 kDa under the nonreducing conditions which was identical with basic 7S globulin (BG). We found that okara was an appropriate material for BG preparation by one-step extraction instead of the previous method [Isolation and characterization of BG have been established by us; Agric Biol Chem, 48, 545 (1984)]. Heat treated okara, however, was inadequate for the material of BG because BG became insoluble probably due to the formation of cross linkage through SS bonds. Pepsin digests of BG and water extracted soybean protein were prepared and fractionated into single peptide by HPLC. Among them, the active peptides with angiotensin I-converting enzyme (ACE) inhibitory activity were screened. One peptide from BG and 4 peptides from water extracted protein digests were obtained. These ACE inhibitory peptides showed the IC50 values ranging 14Å`53 É M. The amino acid sequence of the active peptide from BG was Val-Met-Asp-Lys-Pro-Gln-Gly.


15-6

GLYCEROGLYCOLIPID IN SOY PROTEIN ISOLATE

Seiichi HOMMA and Masatsune MURATA

Department of Nutrition and Food Science, Ochanomizu University

Rep. Soy Protein Res. Com., Jpn. 15, 28-31, 1994.

Soy protein isolate (4kg, SPI) was extracted by 86% ethanol and purified by Iatrobeads column, from which glycolipid was eluted by acetone and methanol. MeOH- and acetone- eluted fractions were then purified by silica gel column chromatography, being eluted with CHCl3/MeOH/water, BuOH/AcOH, and CHCl3/MeOH/NH4OH, and Sephadex LH-20 column chromatography, being developed with MeOH. Each fraction was analyzed by TLC, being detected by Éø-naphthol/H2S04 reagent. The sugar and fatty acid compositions of the obtained eleven fractions were analyzed by acid-hydrolysis. HPLC and GC. The nitrogen contents were also determined. Me-2-b (146mg) and Ac-6-a (76mg), being the major glyceroglycolipids in SPI, were composed of glucose, galactose and palmitic acid (1:1:2), and glucose and palmitic acid (1:1), respectively. Me-1-b was considered to be a sphingoglycosyllipid.


15-7

RELATIONSHIP BETWEEN BEHAVIOR OF CARBONYL COMPOUNDS AND FLAVOR IN SOYBEANS

Teruyoshi MATOBA 1,Hitoshi TAKAMURA 1 and Keisuke KITAMURA 2

1 Department of Food Science and Nutrition, Nara WomenÅfs University
2 National Agriculture Research Center

Rep. Soy Protein Res. Com., Jpn. 15, 32- 35, 1994.

The contents of hexanal and total carbonyl compounds and the behavior of lipoxygenase in the formation of total carbonyl compounds in soybean extracts were elucidated. The proportion of hexanal to total carbonyl compounds in the soybean extract was about 1Å`2%. When the extract was incubated in the presence of exogenous linoleic acid, the contents of hexanal and total carbonyl compounds increased considerably. From the quantitative determination, it was estimated that the proportion of hexanal to total carbonyl compounds derived from linoleic acid by enzymatic action was about 20%.


15-8

EFFECT OF DDMP SAPONIN ON THE FLAVOR AND COLOR OF SOYBEAN FOODS

Kazuyoshi OKUBO and Yumiko YOSHIKI

Faculty of Agriculture, Tohoku University

Rep. Soy Protein Res. Com., Jpn. 15, 36-40, 1994.

Group B (Ba, Bb, Bb', Bc, Bc') and group E (Bd, Be) saponins of soybean have been made clear to be artifact components produced from DDMP (2, 3-dihydro-2, 5-dihydroxy-6-methyl-4 H-pyran-4-one)-conjugated saponins. In this report, it has been definitely shown that DDMP saponins were comparatively stable in acid solution, but easily hydrolyzed in alkaline solution into group B saponins and DDMP derivatives which have an effect on the flavor of soybean foods. Also the DDMP saponins were decomposed by addition of ferric ion into groups B and E (ratio 3 : 2) and brown insoluble complex which has an effect on the color of soybean foods.


15-9

MOLECULAR CLONING OF SOYBEAN CYSTATIN AND ITS EXPRESSION IN E. COLI

Soichi ARAI

Department of Applied Biological Chemistry, The University of Tokyo

Rep. Soy Protein Res. Com., Jpn. 15, 41-44. 1994.

Cystatin is a proteinaceous proteinase inhibitor. We have isolated a cDNA clone for a cystatin from a cDNA library of immature soybean seed and named it soyacystatin. Soyacystatin is comprised of 245 amino acid residues. We constructed four kinds of expression plasmids containing open reading frame of soyacystatin. All the expressed protein in E. coli inhibited papain activity assayed using N-benzoyl-DL-arginine-2-naphthylamide as a substrate. From soybean seeds the fractions containing papain inhibitory activity were partially purified by a series of purification including DE-52, Ultrogel AcA 54, Superose 12 and Mono Q chromatography. Western blotting analysis using antibody to soyacystatin showed that in soybean seeds soyacystatin protein was with a molecular weight of about 26,000.


15-10

EFFECT OF SOY PROTEIN ISOLATE ON FREE RADICAL - INDUCED MUSCLE INJURY UNDER EXERCISE

Takeshi NIKAWA, Takashi YAMAMOTO, Arinobu YAMAUCHI, Takako OHNO,
Kayo NANBA, Yasuhiro KIDO, Kazuhito ROKUTAN and Kyoichi KISHI

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

Rep. Soy Protein Res. Com., Jpn. 15, 45-50, 1994.

Dietary sulfur-amino acids, especially cystine, have been suggested to protect against oxyradical-induced tissue damage. In this study, we examined the effect of soy protein isolate (SPI), whose cystine content is relatively high, on muscle injury under exhaustive exercise. In rats fed 20% SPI diet for 2 weeks, protein concentration in gastrocnemius muscle was higher than that in rats fed casein diet. Five percent SPI diet alleviated the loss of muscle protein as compared with casein diet. SPI diet group showed better exercise performance than casein group as measured by treadmill running. SPI diet significantly suppressed the exercise-induced release of creatine phosphokinase (CPK) from muscle. But SPI diet did not decrease the amount of oxidative products in muscle. The activities of superoxide dismutase and glutathione peroxidase in the muscle increased with exercise, but were not affected by dietary protein source. In conclusion, work capacity was greater and the muscle injury induced by exercise was less in SPI diet group than casein diet group. But SPI diet did not suppress the oxidative stress under exercise.


15-11

EFFECTS OF THE SOYBEAN PEPTIDE ON AN INCREASE IN MUSCLE MASS DURING TRAINING IN MICE

Tohru FUSHIKI, Keitaro MATSUMOTO, Ryohei UOHASHI and Kazuo INOUE

Department of Food Science Åï Technology, Faculty of Agriculture, Kyoto University

Rep. Soy Protein Res. Com., Jpn. 15, 51-56, 1994.

Increase in the muscle mass of mice administered soybean peptide was observed. Mice were fed with commercial diet and 5% soybean peptide solution ad libitum during endurance swimming training every 2 days for 5 weeks. The gastrocnemius and quadriceps muscle masses of the soybean peptide group were larger than those of the control group which was given water instead of the soybean peptide. Amino acid mixture which simulated the soybean peptide gave the same increase in the muscle mass when it was administered to the mouse instead of soybean peptide. The soybean peptide has much branched chain amino acids and glutamine which are reported to stimulate muscle hypertrophy. These results suggested that soybean peptide would stimulate muscle hypertrophy during exercise training with its characteristic amino acid composition.


15-12

ENHANCEMENT OF THE SMALL INTESTINAL TRANSIT AFTER FEEDING OF SOYBEAN PROTEIN ISOLATE (SPI) IN RATS (II)

Hiroshi HARA, Akio HIRATA, Hideki MORIGAMI and Shuhachi KIRIYAMA

Department of Bioscience and Chemistry, Faculty of Agriculture, Hokkaido University

Rep. Soy Protein Res. Com., Jpn. 15, 57-62, 1994.

We previously demonstrated that feeding a low soybean protein isolate (SPI) diet enhances small intestinal transit speed in rats implanted duodenal catheter. Transit speed (geometric center) in rats fed SPI for 10 days is similar to that in rats fed casein diet. The result suggests that the luminal SPI peptides are involved in the enhancement of the transit speed. The difference of the transit speed between casein and SPI-fed rats measured for 12 min was smaller than that measured for 6 min, which suggests that the difference is responsible for the upper small intestine. Jejunal motility (10 and 15cm distal from the ligament of Treitz) as measured by strain gauge-force transducer after feeding a SPI diet was not different from that after feeding a casein diet. The result suggests that the jejunal motility is not involved in the transit speed, or the motility in other part of the small intestine is associated with the enhancement of the transit speed after feeding a SPI diet.


15-13

ABSORPTION OF TWO TYPES OF SOYBEAN PEPTIDES FROM EVERTED SACS OF NORMAL AND INJURED RAT SMALL INTESTINE

Tadao BAMBA, Hwal CHUN, Masaya SASAKI and Shiro HOSODA

Department of Internal Medicine, Shiga University of Medical Science

Rep. Soy Protein Res. Com., Jpn. 15, 63-69, 1994.

In this study the difference of absorption of two types of soybean peptides (small peptide, SP and large peptide, LP) was investigated by using sacs of everted rat jejunum. The everted sacs were incubated for 5 and 10 minutes in bicarbonate-saline buffer containing 1% of each soybean peptide. After the incubation, the amounts of free amino acids and peptides which were transported to the serosal fluids and the mucosa were measured by the automatic amino acid analyzer (Hitachi L-8500) both before and after the hydrolysis of the serosal fluids and mucosa. The result of the present experiment indicated that SP was absorbed more rapidly than LP, and the rapid absorption of SP was due to the larger amount of the intact transport of the peptides in SP. When the everted sacs were made from the rat jejunum which was injured with intraperitoneal injection of cyclophosphamide (300 mg/kg), no significant differences were noted between the absorption of SP and that of LP. We also showed the fact that aminopeptidase inhibitor (BestatinR) decreased the aminopeptidase activities of the rat jejunum. In the presence of 1Å~10-4 M of Bestatin in the incubating buffer, SP was absorbed more rapidly than LP, although smaller amount of both soybean peptides tend to be transported into the everted sacs than in the absence of Bestatin. We conclude that SP can be absorbed more rapidly than LP by rat jejunum in injured intestine as well as in normal intestine.


15-14

SPECIES DEFFERENCE IN THE EFFECTS OF UNDIGESTIBLE FRACTION OF SOY PROTEIN ON PLASMA CHOLESTEROL LEVEL AND FECAL STEROID EXCRETION RATES

Shin-ichi HAYASHI, Youichi MIYAZAKI, Hiroko TAKIZAWA and Sanae TERASAKI

Department of Nutrition, Jikei University School of Medicine

Rep. Soy Protein Res. Com., Jpn. 15, 70-73, 1994.

In mice, unlike in rats and hamsters, soy protein isolate (SPI) does not exert either hypocholesterolemic effect or fecal steroid excretion stimulating effect, compared with casein. Comparison with a non-protein diet indicated that it is SPI, but not casein, that shows differential effects on plasma cholesterol level and fecal steroid excretion between rats and mice. Thus, whereas casein does not stimulate fecal steroid excretion in both rats and mice, SPI stimulates steroid excretion in rats and hamsters, but not in mice. High molecular fraction of undigestible peptides derived from soy protein (HMF) exhibits stronger hypocholesterolemic and steroid excretion stimulatory effects than SPI itself, suggesting that some hydrophobic digestive intermediate(s) of SPI stimulates fecal excretion of steroids, resulting in hypocholesterolemic action. It is conceivable that in mice the hydrophobic digestive intermediate(s) is rapidly hydrolyzed and therefore fails to stimulate steroid excretion and to lower plasma cholesterol level.


15-15

CHARACTERIZATION OF A MAJOR ÅgBILE ACID - BINDING PEPTIDEÅh FROM THE PEPTIC - PANCREATIC DIGEST OF SOYBEAN PROTEIN

Kimikazu IWAMI, Masahiro KANAYA and Fumio IBUKI

Faculty of Agriculture, Kyoto Prefectural University

Rep. Soy Protein Res. Com., Jpn. 15, 74-80, 1994.

Acidic subunits of glycinin (11S globulin) were prepared from defatted soy bean flakes by means of buffer extraction, weak-acid precipitation, ammonium sulfate fractionation and DEAE-Sephadex chromatography, and were digested by using pepsin (at pH 2) and pancreatin (at pH 8). The digestive product was passed through a cholic acid-immobilized Sepharose 4B column. The adsorbed components were eluted with 0.2% deoxycholate and then fractionated by gel filtration with Sephadex LH-20 and Bio-Gel P-10. A major peak-component with apparent molecular weight of about 3,200 was separated by reversed-phase HPLC. Amino acid analysis revealed that the peptide would be composed of glutamic and aspartic acids at the 7 : 3 ratio. Nothing but glutamic acid was released from the peptide by treatment with carboxypeptidase Y. WQEQEDEDED was identified with the aid of a ABI 477A/120A protein sequencer system. It was assumed on the basis of this and other observations that the peptide must have arisen from residues 251-264 of glycinin A3 subunit.


15-16

METABOLIC CHANGES IN LIPIDS AND LIPOPROTEINS OF SERUM INDUCED BY THE ADDITION OF EXCESS DIETARY CYSTINE TO A SOY PROTEIN ISOLATE DIET

Yoritaka AOYAMA, Keizou YUASA, Shigeki FUJII,
Tomohiro ISHIKAWA and Akira YOSHIDA

School of Agricultural Sciences, Nagoya University

Rep. Soy Protein Res. Com., Jpn. 15, 81-84, 1994.

The addition of excess cystine to a soybean protein isolate (SPI) diet caused the accumulation of lipids in the liver. The increase in liver lipids was due to triacylglycerol. In order to know the accumulation of triacylglycerol in the liver, rat hepatocytes were isolated. Triacylglycerol in hepatocytes prepared from rats fed a SPI diet supplemented with cystine was increased, but triacylglycerol in the medium was decreased. The incorporation into triacylglycerol from radioactive glycerol increased in hepatocytes, and decreased in medium. Similar results were observed in phospholipid metabolism. Hepatic apolipoprotein B mRNA was not changed between two groups but the addition of cystine to a SPI diet decreased malic enzyme mRNA. Thus, overall results show that one of the factors for the accumulation of triacylglycerol in the liver induced by the addition of excess cystine to a SPI diet might be due to the decreased transport from liver into serum.


15-17

REGULATION BY SOYBEAN PROTEIN OF Éø- LINOLENIC ACID METABOLISMÅF EFFECT OF HYPERTENSION

Michihiro SUGANO and Akira IKEDA

Faculty of Agriculture, Kyushu University

Rep. Soy Protein Res. Com., Jpn. 15, 85-89, 1994.

The effect of dietary protein on linoleic acid and Éø-linolenic acid desaturation, aortic prostacyclin production and plasma amino acid level was compared in SHR-SP by using soybean protein and casein. Although the desaturation of these polyunsaturated fatty acids and the prostacyclin production were both lowered by soybean protein, the effect of dietary fat type, either safflower oil or perilla oil, was more marked on these parameters than that of dietary protein. There was a highly positive correlation between the linoleic acid desaturation index of phosphatidylcholine and the aortic prostacyclin production. Thus, the protein effect was duplicated even in hypertensive rats.


15-18

EFFECTS OF POLYUNSATURATED FATTY ACIDS AND SOYBEAN PROTEIN ON LIPID METABOLISM OF GENETICALLY OBESE RATS

Nobuko IRITANI, Hitomi FUKUDA and Hiroko HOSOMI

Tezukayama Gakuin College

Rep. Soy Protein Res. Com., Jpn. 15, 90-94, 1994.

The effects of dietary polyunsaturated fat and soybean protein on lipogenic enzyme gene expression of genetically obese Wistar fatty rats have been investigated. The hepatic mRNA concentrations and activities of lipogenic enzymes were greatly increased by feeding a hydrogenated fat diet and reached similar levels between the fatty and lean rats. By feeding a corn oil diet, however, the increases were markedly reduced in the lean rats, but were not significantly reduced in the fatty rats. Consequently, when the animals were fed polyunsaturated fat, the mRNA concentrations and activities in the fatty rats were higher than those in the lean. Thus, it appeared that the higher gene expression in the fatty rats can be ascribed to the defects of polyunsaturated fatty acid suppression. The defects may be one of factors of obesity. On the other hand, the hepatic mRNA concentrations and activities of lipogenic enzymes were significantly decreased by soybean protein in comparison with those of the casein group in both the fatty and lean rats. The plasma triiodothyronine levels were higher in the fatty rat than in the lean, and elevated by feeding soybean protein. Conversely related to the triiodothyronine levels, the plasma triacylglycerol levels were decreased by soybean protein in both the fatty and lean rats. Thus, it is suggested that dietary soybean protein can contribute to reduce the triacylglycerol levels due to the increase of triiodothyronine levels as well as the suppression of lipogenic enzyme gene expression in the genetically obese Wistar fatty rats.


15-19

EFFECTS OF SOY PROTEIN ISOLATE ON HIGH SUCROSE - AND HIGH FAT - INDUCED OBESITY IN POST - WEANING RATS

Eiko HARA 1,Yasutake SHIMIZU 2 and Takashi SHIMAZU 2

1 Imabari Meitoku Junior College
2 Department of Medical Biochemistry, School of Medicine, Ehime University

Rep. Soy Protein Res. Com., Jpn. 15, 95-98, 1994.

Effects of dietary soy protein isolate (SPI) on high sucrose- and high fat- diet induced obese model were examined in post-weaning rats. The rats were fed 30% sucrose and 20% soybean oil for 2 weeks. High fat diet increased the serum triglyceride concentrations but the suppressive effect of SPI on serum triglyceride was not observed in rats fed high fat diet. Thermogenic activity of brown adipose tissue (BAT) was also examined by measuring the uncoupling protein (UCP) content in the mitochondria with the use of immunoblotting. UCP contents were increased in SPI-fed rats, suggesting that SPI contributes to the prevention of the development of dietary obesity in weaning rats with high sucrose and high fat diet.


15-20

ALLERGENICITY OF GLYCOSIDE RESIDUES IN SOYBEAN PROTEIN ISOLATE AND ITS IMPROVEMENT BY DEGRADATION INTO PEPTIDES

Misako TANIGUCHI 1, Mamoru FUJITA 1, Takami FUSANO 1, Akane KOMATSU 1,Chinami YANO 1 and Shinpei MORITA 2

1 Department of Food and Nutrition, Nakamura Gakuen College
2 Central Research Institute, Fuji Oil Company

Rep. Soy Protein Res. Com., Jpn. 15, 99-103, 1994.

To suckling rats, soybean protein (SPI) or soybean peptide (PM) mixed with Freund's adjuvant was intraperitoneally injected, or SPI mixed with corn oil was orally administered three times every other day starting from 10 days after birth. After weaning, the rats were fed a SPI diet for 5 weeks and IgG specific for SPI in the serum was determined by ELISA. A large quantity of anti-SPI-IgG was produced when SPI was given to rats intraperitoneally, while no SPI specific IgG was detected by administration of PM. In contrast, anti-SPI-IgG was produced only in a small quantity when SPI was administered orally. After separating by SDS-PAGE, each subfraction of soybean protein was blotted on nitrocellulose membrane. Then, the membrane was incubated with the serum, and anti-IgG specific for respective subfraction was analyzed by immunostaining. It was found that 7S É¡ and É¿, 11S acidic and basic, and 2S produced a large quantity of anti-IgG specific for each protein when SPI was intraperitoneally injected. On the other hand, 7S É¡, 11S basic, and 2S were strong antigens when SPI was administered orally. Using electron microscopy, it was found that peroxidase-labeled 7S É¿ was taken up by coated pit of microvillous membrane, then transferred by vesicle, and further released to the basolateral surface.


15-21

PREPARATION OF HYPOALLERGENIC SOYBEAN PRODUCTS

Tadashi OGAWA, Hideaki TSUJI and Noriko BANDO

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

Rep. Soy Protein Res. Com., Jpn. 15, 104-108, 1994.

A major allergenic protein (Gly m Bd 30K) in soybean has been identified as 34-kDa oil-body-associated protein. Prior to the development of hypoallergenic soybean products, we prepared first the allergen-specific paper disk for radioallergosorbent test and established the Sandwich-ELISA method for a quantitative analysis of the allergen in soybean products using two distinct monoclonal antibodies, F5 and H6. Moreover, in order to get the information about the active sites of allergen, the epitope sequence recognized by patient's sera was estimated using the enzyme-digested and CNBr-degraded allergen fragments.


15-22

IMMUNOLOGICAL RESPONSE AND TO LERANCE TO DIETARY SOYBEAN PROTEIN

Tsukasa MATSUDA, Tetsuya ISHII, Naohito AOKI and Ryo NAKAMURA

School of Agricultural Sciences, Nagoya University

Rep. Soy Protein Res. Com., Jpn. 15, 109-114, 1994.

Immune response of mice to soybean protein and its modification by pre-feeding with soybean protein were investigated to get information on immunogenic properties of soybean protein. Mice fed with a non-purified diet were divided into two groups based on serum antibody level to soybean protein, i. e., responder and non-responder mice. The primary antibody response to soybean protein injected i. p. tended to be low for the non-responders and high for the responder mice, though there were some exceptions in each group. Serum antibody response to soybean protein injected i. p. was markedly lower than the response to injected egg white protein. Mice fed with purified diets containing milk protein or egg white protein showed antibody response to these fed proteins, whereas mice fed with soybean protein-containing diet showed no response to the soybean protein antigen. These results suggest that soybean protein is less immunogenic and more tolerogenic than egg white and milk proteins.


15-23

EFFECT OF SOY PROTEIN ISOLATE (SPI) AND EXERCISE TRAINING ON THE DECREASE OF CELLULAR IMMUNE FUNCTIONS WITH AGING

Yasuo KISHINO, Satoru MORIGUCHI and Naoko OKISHIMA

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

Rep. Soy Protein Res. Com., Jpn. 15, 115-119, 1994.

The purpose of this study was to determine the effect of soybean protein isolate (SPI) and exercise training on the decrease of cellular immune functions with aging. Male Fischer rats, 3 (young) and 15 (old) months old, were fed a diet containing 20% casein or 20% SPI, and trained on a treadmill at 10 m/min, 30 min/day, 5 days/week for 4 weeks. Proliferations of peripheral blood lymphocytes (PBL) with phytohemagglutinin (PHA) and concanavalin A (Con A) were remarkably decreased in old rats compared to those of young rats regardless of the difference of dietary protein. Exercise training improved proliferation of PBL with Con A in old rats to the level of sedentary young rats, whereas proliferation of PBL with PHA was improved only in old rats of SPI group by exercise training. The proportions of T cell subsets (helper T cell, Th and suppressor T cell, Ts) in PBL of SPI group were higher than those of control group in both young and old rats. The production of interleukin 2 (IL2) from splenocytes agreed with the results of PBL proliferation with PHA and Con A in young rats, whereas the production of IL2 from splenocytes of old rats was higher than that of young rats in both control and SPI groups, and was in conflict with the results of PBL proliferation with PHA and Con A. These findings suggest that exercise training can improve the decrease of cellular immune functions with aging, which is not associated with the production of IL2, and that SPI diet also improves the decrease of cellular immune functions in old rats through an increased proportion of Th cells and an increased production of IL1 from macrophages.


15-24

FORMULATION AND EVALUATION OF A SPECIAL DIET FOR DIABETES EMPLOYING SPI AS THE PRINCIPAL SOURCE OF PROTEIN

Tadashi NOGUCHI, Hiroshi DANNO, Asako TAKENAKA and Shin-ichiro TAKAHASHI

Department of Applied Biological Chemistry, The University of Tokyo

Rep. Soy Protein Res. Com., Jpn. 15, 120-123, 1994.

A special diet for the experimentally induced diabetic rats was formulated employing SPI as the principal source of protein. The diet contained less branched chain amino acids compared with the recommended requirement for rats by National Research Council, U.S.A. When streptozotocin-injected diabetic rats were fed on this formulated diet, the body weight loss of the rats improved and urinary nitrogen excretion decreased compared to the rats fed on a casein diet. Plasma glucose concentration was significantly lower and plasma immunoreactive insulin concentration was significantly higher in the rats given the formulated diet than those fed on the casein diet. These results show that SPI is an excellent source of dietary protein for diabetic animals.


15-25

EFFECT OF SOY PROTEIN ON RENAL HEMODYNAMICS AND URINARY ALBUMIN EXCRETION IN SPONTANEOUSLY DEVELOPED DIABETIC WBN/Kob RATS

Yoshio IKEDA 1 and Yutaka MORI 2

1 Department of Preventive Medicine, Center for General Health Care,Jikei University School of Medicine
2 Department of Internal Medicine, Jikei University School of Medicine

Rep. Soy Protein Res. Com., Jpn. 15, 124-129, 1994.

To investigate the effects of protein loading on renal hemodynamics and urinary albumin excretion (UAE), diabetic WBN/Kob and control Wistar rats aged 10 months were given 40% protein diets from different sources and observed for 4 weeks using metabolic cages. Rats were fed control diet in the 1st week, 40% soy protein diet in the 2nd week, 40% pork protein diet in the 3rd week and 40% soy protein diet in the 4th week. UAE in 40% pork protein diet-fed period significantly decreased compared with those in 40% soy protein diet-fed periods in both WBN/Kob and Wistar rats. Urinary prostaglandin E2 (PGE2) excretion and creatinine clearance rate (Ccr) as an index of glomerular filtration rate in 40% pork protein diet-fed period also decreased significantly compared with those in 40% soy protein diet-fed periods in both WBN/Kob and Wistar rats and the change of urinary PGE2, excretion was well correlated with those of Ccr and UAE. In contrast with the previous reports, these results suggest that vegetable protein might have more influence on the renal hemodynamics and UAE than animal protein.


15-26

EFFECT OF SOYBEAN WHEY PROTEIN ON HEPATOMA IN RATS

Rie SEMURA, Katsumasa SHIMADA, Katsuyuki KATO, Yoshihide OHSHIRO,Sumie SHINJO and Shigeru YAMAMOTO

Research Center of Comprehensive Medicine, University of the Ryukyus

Rep. Soy Protein Res. Com., Jpn. 15, 130-133, 1994.

In the previous experiment we found the anti-tumor effect of soybean whey protein in mice. In this experiment we studied the effect of soybean whey protein on chemically induced hepatoma in rats. Rats were given commercial laboratory chow supplemented with 2% soybean protein isolate or soybean whey protein and water or water containing chemical carcinogen for 16 weeks. Percentage of the rats with hepatoma was significantly lower in soybean whey protein group than soybean protein isolate group, indicating the anticarcinogenic effect of soybean whey protein.


15-27

PROTEINS FROM DIFFERENT SOURCES CAUSE A DIFFERENCE IN THE PROGRESS OF HEPATITIS AND HEPATIC CANCER IN THE LONG - EVANS CINNAMON (LEC) RATS ÅF AN ANIMAL MODEL FOR HEPATITIS AND HEPATIC CANCER (1) FEEDING LEC RAT A SOY - PROTEIN DIET WITH OR WITHOUT ADDITION OF METHIONINE

Naoki SUGAWARA 1, Chieko SUGAWARA 1, Dan LI 1, Hirotugu MIYAKE 1,Michio MORI 1 and Akihiro YAMAGUCHI 2

1 School of Medicine, Sapporo Medical University
2 Sapporo City Institute of Public Health

Rep. Soy Protein Res. Com., Jpn. 15, 134-139, 1994

The LEC rat is a mutant strain which develops hereditary hepatitis and hepatic cancer. An abnormal copper metabolism in the liver is, perhaps, responsible for the hepatitis. This strain has a high susceptibility to chemical carcinogens even though copper accumulation is protected against. If it is understood why they are vulnerable to carcinogens, the rats may be a useful model animal for screening cancer-promoting factors; for example nutritional circumstances. It is known that a deficiency in available methyl groups can result in hepatitis and hepatic cancer. In this experiment, female LEC rats (45 days old) were fed a soy-protein diet with or without addition of 0.3% methionine for 26 days. The ability to utilize the amino acid was evaluated from the concentration of the serum amino acid. The hepatic copper concentration of LEC rats was 35 times that of Fischer rats at the end of feeding. However, addition of methionine to the food increased food efficiency not only in Fischer but also in LEC rats. Addition of methionine did not increase the serum concentration of the amino acid. When these results were considered, it appears that a disability in methionine-activation process may not precede the hereditary hepatitis of the LEC rat.


The soy protein protein reserch(Japan)