Solubility of soy lipophilic proteins: comparison with other soy protein fractions

Solubility of soy lipophilic proteins (LP) was studied as compared with that of other soy protein fractions. LP, β-conglycinin, glycinin, and soy protein isolate (N-SPI) were prepared under the condition to avoid heat denaturation. Solubility of LP was lower than that of other soy protein fractions under all the tested conditions varying in pH values and ionic strength. The solubility of LP was increased constantly by elevating temperature until 90 °C, whereas that of β-conglycinin and glycinin dropped at high temperature. Temperature-dependent change in solubility of N-SPI might reflect the balance among that of glycinin, β-conglycinin and LP. Based on the results of SDS-PAGE, determination of phospholipid content and Fourier Transform Infrared spectroscopy, we discussed the solubilization behavior of LP relating to its origin and composition.     

Effects of alginates on the ingestion and excretion of cholesterol in the rat

The effects of three forms of alginate (free acid, sodium and calcium salts) on ingestion and excretion of cholesterol in the rat were studied. For two weeks, Male Sprague-Dawley rats were fed a cholesterol-rich diet containing 3% alginate from the brown alga Ascophyllum nodosum. The food efficiency of the three types of alginate was: Na-alginate > Ca-alginate > alginic acid. A significant increase in the weight of cecum was also observed in alginate diets. Alginate was not effective in preventing the elevation of serum total cholesterol levels, although irregularly changing patterns were observed. The cholesterol level of liver showed a tendency to decrease with alginate feeding, while fecal excretion of cholesterol increased.     

Effects of soy protein diet on the expression of adipose genes and plasma adiponectin.

Many studies have reported the cholesterol-lowering, anti-lipogenic, anti-obesity and anti-hypertensive effects of soy protein. Adipose tissue-specific plasma protein, adiponectin, has anti-atherogenic and anti-insulin-resistance properties. Here, we investigated the effects of soy protein diet on body fat composition, plasma glucose, lipid and adiponectin levels and expression of genes involved in glucose and fatty acid metabolism in obese KK-A y mice. Body weights and adipose tissue weights of mesenteric, epididymal, and brown fat were lower in mice on calorie-restricted diet containing soy protein isolate. Plasma cholesterol, triglyceride, free fatty acid, and glucose levels were also decreased by this diet. Body fat content and plasma glucose levels in mice on a soy protein isolate diet were still lower than those treated with an isocaloric casein-protein-diet. Among the genes related to glucose and fatty acid metabolism, adiponectin mRNA levels in adipose tissue and adiponectin plasma concentrations were elevated in mice on a calorie-restricted diet, although there were no significant differences between soy protein and casein protein groups. Our results indicate that that soy protein diet decreased body fat content and plasma glucose levels more effectively than isocaloric casein-protein diet in obese mice.     

大豆蛋白、苹果果胶及维生素C 排铅效果的探究

通过对铅中毒小鼠灌胃三种不同剂量的食物材料,探究大豆蛋白、苹果果胶及维生素C的排铅效果。实验通过每日对铅中毒小鼠喂食高、中、低三种不同剂量的苹果果胶、大豆蛋白和维生素C,连续28 d。然后收集小鼠的血液、肝脏和股骨,用原子吸收光谱仪进行铅检测。结果表明重金属铅的摄入会影响小鼠的健康和生长状况;大豆蛋白、苹果果胶和维生素C均具有一定的排铅效果,在最佳的条件下,血铅含量降低了65%~70%,肝脏铅含量下降了63%~85%,股骨铅含量下降了18%~26%。本实验证明大豆蛋白、苹果果胶及维生素C三种食品材料具有较好的降血铅效果,维生素C被认为是最适合用于开发排铅功能食品的原料。本研究为排铅功能食品的研发提供了重要的理论依据。     

Interactions of different phenolic acids and flavonoids with soy proteins

Soy glycinin (SG) and soy trypsin inhibitor (STI) were derivatized by chlorogenic- and caffeic acid (cinnamic acids, C(6)-C(3) structure), and by gallic acid representing hydroxybenzoic acids (C(6)-C(1) structure). Further, the flavonoids, flavone, apigenin, kaempferol, quercetin and myricetin (C(6)-C(3)-C(6) structure) were also caused to react with soy proteins to estimate the influence of the number and the position of hydroxy substituents. The derivatization caused a reduction of lysine, cysteine and tryptophan residues in the soy proteins. The isoelectric points of the derivatives were shifted to lower pH values and formation of high molecular fractions was documented. The derivatives were characterized in terms of their solubility at different pH-values to document the influence on the functional properties. The structural changes induced were studied using circular dichroism (CD), differential scanning calorimetry (DSC), intrinsic fluorescence, and binding of anilinonaphthalenesulfonic acid. The influence of derivatization on the in-vitro digestibility with trypsin, chymotrypsin, pepsin and pancreatin was also assessed. The effect on the trypsin inhibitor activity of all the resulting STI derivatives was studied, the latter being reduced.     

不同有机无机复混肥对水稻产量和氮素利用率的影响

通过田间试验,研究了菜粕堆肥、猪粪堆肥和中药渣堆肥有机无机复混肥与化肥对常优1号水稻产量、氮素利用效率、土壤供氮特征以及土壤微生物多样性的影响.结果表明：各施氮肥处理的稻谷产量（7918.8～9449.2 kg·hm^-2）均显著高于对照（6947.9 kg·hm^-2）,其中有机无机复混肥处理的稻谷产量(8532.0～9449.2 kg·hm^-2)显著高于化肥处理（7918.8 kg·hm^-2）,比化肥处理增产7.7%～19.3%;菜粕堆肥、猪粪堆肥、中药渣堆肥有机无机复混肥处理的氮素积累量、氮素转运率、氮素回收率和氮肥农学利用效率及生理利用效率均显著高于化肥处理;有机无机复混肥处理明显提高了土壤矿质氮含量,改善了土壤供氮特性,提高了氮利用率;对各处理土壤DNA条带采用邻接法分析显示：5个处理土壤样品可分为三大族群,化肥与对照处理为第一族群,猪粪堆肥、中药渣堆肥处理为第二族群,菜粕堆肥处理属第三族群.表明施入外源有机物质(菜粕、猪粪与中药渣)可能会改变土壤的细菌群落结构,而施入化肥对土壤的细菌群落结构影响较小.     

Effects of soy protein on alcoholic liver disease in rats undergoing ethanol withdrawal

ObjectiveThis investigation attempted to clarify the effects of soy protein on alcoholic liver disease (ALD) in rats undergoing ethanol withdrawal.MethodsAlcoholic liver disease was induced in rats by administration of a low-carbohydrate ethanol liquid diet for 12 weeks, after which the ethanol was withdrawn and the rats were divided into two experimental groups: a control group (EC group) and a soy protein group (EP group) for 4 weeks.ResultsAfter the 12-week ALD-inducing period, the ethanol group had significantly higher hepatic lipid accumulation, oxidative stress and inflammation. We found that the EP group had significantly lower hepatic lipids, malondialdehyde, tumor necrosis factor-α, interleukin (IL)-1β, IL-6, hydroxyproline levels and myeloperoxidase activity compared to the EC group. Moreover, the fecal total cholesterol and total lipids were higher in the EP group. Expression of the hepatic cytochrome P450 2E1 (CYP2E1) protein in the EP group was significantly lower than that in the EC group, and the hepatic peroxisome proliferator-activated receptor (PPAR) α and cytochrome P450 4A (CYP4A) protein expressions in the EP group were significantly higher than those in the EC group. In the histopathological analysis, we also found that soy protein ameliorated fat accumulation in the liver.ConclusionThese results suggest that soy protein may improve alcohol-induced lipid accumulation, oxidative stress and inflammation by decreasing proinflammatory cytokines and CYP2E1 protein expression and by increasing PPARα and CYP4A protein expressions and fecal lipid excretion, thereby producing beneficial effects on ALD during ethanol withdrawal.     

A study of the chain stiffness and extension of alginates, in vitro epimerized alginates, and periodate-oxidized alginates using size-exclusion chromatography combined with light scattering and viscosity detectors

A series of alginates isolated from the stem and leaf of a brown algae (Laminaria hyperborea), bacterial mannuronan, in vitro epimerized mannuronans, and periodate oxidized alginates were analyzed by size-exclusion chromatography (SEC) combined with online multiangle laser light scattering (MALS) and viscometry (collectively abbreviated SMV). Selected samples were also analyzed off-line using low-angle laser light scattering and capillary viscometry. Excellent agreement between the two methods was obtained for properly purified samples. In contrast, abnormal results were obtained for some industrial samples due to the presence of particulate material. Naturally occurring alginates and in vitro epimerized mannuronans were found to obey essentially the same RG-M and [eta]-M relations, and hence, the same Mark-Houwink-Sakurada (MHS) equations (valid for I = 0.10 M): 20 000 g/mol < M < 100 000 g/mol, [eta] = 0.0054 .M(1.00); 100 000 g/mol < M < 1 000 000 g/mol, [eta] = 0.071 .M(0.89). Application of the wormlike chain model to the [eta]-M data obtained by SMV yielded persistence lengths (q) of 15 nm for all alginates at an ionic strength of 0.17 M. Intrinsic viscosities corresponding to infinite ionic strength were estimated on the basis of Smidsr?d's B-parameter, and the wormlike chain model then yielded q = 12 nm. Periodate oxidized alginates showed, in contrast, a pronounced decrease in persistence length with increasing degree of oxidation, reaching values below 4 nm at 44% oxidation. Periodate oxidation also resulted in some depolymerization, even in the presence of a free-radical scavenger.     

Effects of freezing and protein cross-linker on isolating membrane raft-associated proteins

Since the discovery of cellular membrane rafts, the defining of these domains has remained ambiguous due to a great number of isolation procedures proposed for the extraction of the rafts from cells. Characterization of membrane rafts using Triton X-100 insolubility is limited by the fact that weak interactions between proteins and lipids within the membrane rafts cannot be detected. In order to study the role of membrane rafts in cell signal transduction, it is crucial that weak membrane raft-associated proteins are detected. In this report, we demonstrate that by incorporating 3,3'-dithiobis(sulfosuccinimidyl propionate) (DTSSP) crosslinking and freezing at -80°C into the membrane raft isolation procedure of HaCaT cells, both membrane raft-associated proteins caveolin-1 and Fas receptor are able to be reproducibly isolated into a single fraction containing the membrane rafts of the cells.     

Role of soy isoflavones in the hypotriglyceridemic effect of soy protein in the rat

The present study was undertaken to determine whether isoflavones present in soy protein isolate contribute to the triglyceride-lowering effect of the protein relative to casein. Plasma triglyceride concentrations, their secretion rate into blood circulation, and post-heparin plasma lipoprotein lipase activity (a major determinant of intravascular catabolism of triglycerides) were measured in the fasted state in male Sprague-Dawley rats fed for 21 days one of three experimental diets varying in protein source (20% weight/weight): soy protein isolate, casein or casein to which 1.82 mg/g isoflavones (genistein and daidzein) were added to match the isoflavone content of soy protein isolate. Body weight gain was slightly lower in soy protein fed rats than in casein fed rats, but this effect was not statistically significant (P = 0.22). Casein plus isoflavones diet induced intermediary weight gain. A decrease in plasma total triglycerides was observed in rats fed soy protein and casein plus isoflavones compared with casein (P < 0.05), and there was a tendency to a positive correlation between weight gain and plasma triglyceride concentrations (r = 0.35, P = 0.06). However, no significant effect was observed on hepatic triglyceride concentrations, triglyceride secretion rate by the liver and post-heparin plasma lipoprotein lipase activity. These results show that soy protein isolate, in comparison with casein, has a hypotriglyceridemic effect in the rat and suggest that isoflavones may be responsible, at least in part, for this effect. The lowering effect of soy protein isolate and isoflavones on plasma triglyceride concentrations may be mediated by an alteration in energy balance, and possibly by the hepatic production of lipoproteins more susceptible to intravascular hydrolysis. Subtle but sustained changes in triglyceride secretion and post-heparin plasma lipoprotein lipase activity may also be implicated.     

Effects of soy protein diet on digestive lumenal polyamines and colonic cell proliferation in pigs.

This study was performed to determine whether erythrocyte and digestive lumenal polyamine concentrations are affected by a soy protein diet when compared to a casein diet. We also determined the effects of these diets on colonic cell proliferation. Sixteen pigs received either a 16% soy protein or casein diet for 25 days. The erythrocyte putrescine was higher in pigs fed the soy protein diet. Significant levels of polyamines were observed in the digestive lumen on both diets. Lumenal putrescine and cadaverine were higher in the proximal colon in the casein group. Lumenal spermidine was higher in the caecum and colon in the soy protein group. No significant differences in the ornithine decarboxylase activity nor in the proliferative cell nuclear antigen labelling index were observed in the colonic mucosa regardless of the regimen. These results indicate that the dietary source of protein induces significant changes in lumenal polyamines in the colon. The physiological effects of these changes need to be further investigated.     

Effects of a high soy protein diet on intestinal polyamines and ornithine decarboxylase activity in rats

This study was performed to determine whether intestinal luminal polyamine concentrations are affected by a high soy protein diet when compared with a high casein diet or a normoprotein casein diet. We also determined the effects of these diets, with differences in polyamines content, on mucosal polyamines and ornithine decarboxylase (ODC) activity to assess cell proliferation. Three groups of eight male Wistar rats were fed either a 50% soy protein diet, a 50% casein diet, or an 18% casein diet as a control. After 4 weeks of feeding, both intestinal content and mucosa were recovered. Polyamines were assayed by high performance liquid chromatography. ODC activity was measured by the release of (14)CO(2) from (14)C-L-ornithine. Luminal putrescine and cadaverine concentrations were higher in the jejunum than in the ileum, suggesting an absorptive process. The highest concentrations of intestinal polyamines were observed in rats fed the soy protein diet (P < 0.05). Only minor differences were observed in mucosal polyamines according to the diets. ODC activity was also higher in the intestinal mucosa of rats fed the high soy protein diet (P < 0.05). These results suggest that intestinal luminal polyamine concentrations and ODC activity are modulated by the dietary protein source.     

单播与混播对两个冬小麦品种产量和水分利用效率的影响

选取黄土旱塬两个冬小麦品种长武135和平凉40,采用生态替代法连续两年在田间条件下研究了单播和混播方式对冬小麦产量和水分利用效率的影响.结果表明:单播条件下平凉40单位面积根量为367.60 g·m-2,显著大于长武135的297.31 g·m-2,且其根系在各土层中分布较均匀,表明与长武135相比,平凉40吸收土壤水分的能力较强,但其在单播条件下的产量和水分利用效率较低.混播增加了平凉40和长武135根系在较深土层中的根量分布,两品种根量分别比单播条件下多13.36和8.50 g·m-2,混播增强了小麦根系对深层土壤水分的吸收利用,提高了单位面积总产量,增加了群体水分利用效率.与平凉40相比,长武135分配了更多的干物质到繁殖器官,使其根量和地上营养器官的生物量减小,从而提高了籽粒产量和收获指数,表现出较高的水分利用效率.     

The effect of limited hydrolysis with Neutrase and ultrafiltration on the anti-adipogenic activity of soy protein

Limited hydrolysis of isolated soy protein (ISP) with Neutrase for 4 h to obtain the hydrolysate (NH4h) revealed the ability to suppress glycerol-3-phosphate dehydrogenase (GPDH) activity and relative lipid accumulation (RLA) in 3T3-L1 cells during differentiation. Lower GPDH activity or RLA indicates higher anti-adipogenic activity. Sequentially fractionating NH4h with 30–1 kDa (kilo-daltons) molecular weight cut-off (MWCO) membranes to obtain the 1 kDa concentrate resulted in further enhancing its anti-adipogenic activity in the cells. The GPDH activity significantly decreased from 280 to 100 U/mg protein (p < 0.05). When comparing the high-performance size-exclusion chromatography (HPSEC) profiles, the most active peptide for the anti-adipogenic activity was primarily composed of peptides with molecular weight between 1300 and 2200 Da. The in vitro effect of gastrointestinal protease on the anti-adipogenic activity of 1 kDa concentrate was also investigated. The results suggested that gastrointestinal proteases have very little effect on anti-adipogenic activity of the concentrate. According to the Western immunoblot analysis, 1 kDa concentrate inhibits adipogenesis by affecting the expression of peroxisome proliferators-activated receptor γ (PPARγ) and the CCAAT/enhancer binding protein α (C/EBPα) during 3T3-L1 cells differentiation.     

Effects of soy protein and isoflavone on hepatic fatty acid synthesis and oxidation and mRNA expression of uncoupling proteins and peroxisome proliferator-activated receptor gamma in adipose tissues of rats

Soy protein rich in isoflavones profoundly affects lipid metabolism in experimental animals. To distinguish the roles of the protein and isoflavone components of a soy protein preparation in regulating lipid metabolism, we compared the effects of diets containing methanol-washed soy protein low in isoflavone supplemented with a 0-, 0.5- and 4-g/kg isoflavone preparation on hepatic fatty acid metabolism and adipose tissue gene expression in rats. Diets containing soy protein irrespective of the isoflavone levels decreased the activities and mRNA expression of enzymes involved in hepatic fatty acid synthesis to similar levels. Methanol-washed soy protein compared to casein increased the mRNA expression of peroxisome proliferator-activated receptor (PPAR) alpha, and supplementing the soy protein diet with isoflavone further increased this parameter dose-dependently. However, methanol-washed soy protein compared to casein was totally ineffective in altering the activities and mRNA levels of enzymes involved in fatty acid oxidation. Supplementation of soy protein diets with isoflavone slightly increased these parameters. The mRNA level of uncoupling protein (UCP) 1 in brown adipose tissue was significantly increased and mRNA levels of UCP2 and 3, and PPARgamma2 tended to be higher in rats fed methanol-washed soy protein not supplemented with isoflavone than in the animals fed casein. Adding isoflavone to the soy protein diets dose-dependently increased these parameters. These results suggested that the protein rather than isoflavone component is primarily responsible for the physiological activity of soy protein rich in isoflavones in reducing hepatic lipogenesis. However, isoflavones may have a role in regulating heptic fatty acid oxidation and adipose tissue gene expression.     

Studies on the nature of interaction of iron(III) with alginates

The interactions between the polysaccharide alginate and iron(III) were investigated. The solution properties were studied through pH-metry, viscometry, zeta potential and particle size measurements. In the presence of alginate, iron(III) was stabilized and no precipitation was observed. Studies indicate that iron(III)-alginate system was more stable than iron(III) or alginate alone. The binding constant is of the order of 10(4) M(-1). A case for 'site binding model' for the interaction between alginate and Fe(III) has been made based on the studies using circular dichroism and zeta potential experiments. The number of binding sites per molecule of alginate has been estimated to be 66. This indicates that the alginate can bind more number of Fe(III) ions and thus provide a stable complex which can find wide industrial applications.