3种进化类型大豆叶片的某些生理特性比较

半野生、半栽培和栽培大豆叶片可溶性糖和可溶性蛋白含量以及过氧化物酶（POD）和超氧化物歧化酶（SOD）活性均表现为随品种的进化而增加的变化趋势。POD活性在生育期中呈上升变化,SOD活性则随着生育进程逐渐下降。栽培大豆的可溶性糖含量和POD活性以上部叶片最高,半栽培大豆与栽培大豆类似,半野生大豆的变化则不明显。     

大豆叶片质膜蛋白激酶的自身磷酸化反应

利用Ferrell和Martin（1991）设计的测定印迹在PVDF膜上的蛋白激酶活性方法研究大豆叶片质膜蛋白激酶自身磷酸化反应活性,结果表明：与Mg－ATP相比,Mn－ATP是更有效的57KD蛋白激酶自身磷酸化反应底物;钙离子可以促进该激酶的自身磷酸化反应活性,而且EGTA可以显著降低它在SDS电泳中的迁移率,说明57KD蛋白激酶为依赖于钙的蛋白激酶;预磷酸化反应实验证明57KD蛋白激酶具有多个自身磷酸化反应位点,其分子的自身磷酸化状态可调性暗示这一激酶可能具有重要的生理功能。     

Characterization and Functional Properties of Sub-Fractions of Soluble Soybean Polysaccharides

Soluble soybean polysaccharide (SSPS) was fractionated into two sub-fractions, a high-molecular-weight fraction (HMF) and a low-molecular-weight fraction (LMF) by the ethanol-extraction method. Characterization of the sub-fractions, that is, analysis of chemical composition, gel filtration, and SDS–PAGE, revealed that the main component of HMF was a large polysaccharide molecule with covalently-attached peptides, possibly corresponding to the intact SSPS molecule. LMF consisted of free peptides and saccharides of small size, which might have occurred as by-products during the production process of SSPS. HMF exhibited high ability to emulsify oil droplets and stabilize α-casein dispersions in an acidic pH region, but this ability of LMF was inferior to HMF. On the other hand, LMF had higher activity to prevent the oxidation of emulsified lipids than HMF. These results suggest that HMF and LMF had different characteristics and functional properties, and that the combination of the two sub-fractions generates the multi-functions of commercial SSPS.     

Soluble carbohydrate content of soybean [Glycine max (L.) merr.] somatic and zygotic embryos during development

Summary Somatic and zygotic embryos of soybean cv. Jack were analyzed for soluble carbohydrate, total lipids, and protein during development. Zygotic embryos accumulated trace amounts of fructose, galactose, and galactinol., whereas somatic embryos contained only trace amounts of galactose. Somatic embryos accumulated much higher glucose levels than zygotic embryos. Both somatic and zygotic embryos contain low levels of sucrose, myoinositol, and pinitol. Raffinose and stachyose accumulated in the late developmental stages of zygotic embryos, but only stachyose was found to accumulate in the late stage somatic embryos. Zygotic embryos contained low total lipid levels up to 50 d after flowering (DAF) and then the levels increased to 16% by 55 DAF and 21% at 65 DAF. Somatic embryos had low levels of total lipids throughout development with the maximum of only 4.7%. Soybean zygotic embryos contained about 40% protein throughout development, while the protein concentration of somatic embryos decreased from 44% to 25% as maturation approached. These studies demonstrate that the composition of Jack zygotic embryos is similar to that described for other cultivars during development while the somatic embryo composition and size is markedly different. The low somatic embryo germination often noted might be due to the abnormal development as shown by a composition different from that of mature zygotic embryos. The low concentration of the raffinose series sugars might be especially important factors.     

l-Sorbose Oxidase from Trametes sanguinea

A crude inhibitor for pancreatic lipase was extracted from soybean seeds. The lipase activity decreased curvilinearly with an increase in inhibitor concentration. At a low inhibitor concentration, enhanced inhibition was observed by the co-existence of protein such as bovine serum albumin in the reaction mixture. The lipase activity was inhibited immediately after the addition of inhibitor which did not cause the significant destraction of substrate emulsion. The lipase activities of Aspergillus niger, Rhizopus delemar and castor bean seeds were also inhibited. The inhibition was observed when various oil substrates such as soybean oil, linseed oil, olive oil emulsions and Ediol were used, and the extent of inhibition varied among them. Column chromatography of inhibitor on Sephadex G–100 showed that the molecular weight of a main peak of inhibitor was estimated as about 80,000.     

Cysteine uptake and taurine biosynthesis in freshly isolated and primary cultured rat hepatocytes

Analysis of the uptake and metabolism of [14C]cysteine in rat liver was undertaken using freshly isolated hepatocytes and hepatocytes maintained in primary culture. The uptake of [14C]cysteine by freshly isolated hepatocytes was by means of both saturable and non-saturable transport systems and the former system was thought to involve facilitated diffusion. The uptake of [14C]cysteine by hepatocytes maintained in primary culture for 24 h also consisted of non-saturated and saturated transport mechanisms. The magnitude of the saturable transport system in cultured hepatocytes was, however, much greater than that found in freshly isolated hepatocytes, and was considered to be operated by active transport. Both freshly isolated and primary cultured hepatocytes had cysteine sulphinic acid decarboxylase activity, but this enzyme activity in the latter cells was noticeably reduced in comparison with that found in freshly isolated hepatocytes. Hepatocytes maintained in primary culture produced not only radiolabelled taurine, but also radiolabelled cysteine sulphinic acid, hypotaurine and alanine when incubated with [14C]cysteine. The present results indicate that cultured hepatocytes actively transport cysteine as well as metabolizing cysteine to taurine via cysteine sulphinic acid and hypotaurine.     

Effect of the application of selenium on selenium content of soybean and its products

Two experiments were conducted to study the effect of the application of selenium on the selenium content of soybean and its products in two counties with selenium-deficient soil. Selenium-enriched soybean was produced by the application of sodium selenite and Se-enriched fertilizer. The selenium contents of soybeans, soybean protein and okra were determined by hydride-generation atomic fluorescence spectrometry. The results showed that the selenium contents of soybean, soybean protein, and okra were significantly increased by the application of sodium selenite and selenium-enriched fertilizer. Foliar application of selenium provided a higher efficiency for increasing the selenium content of soybean than soil application. Significant differences were found in that soybean cultivars exhibited different accumulation of selenium. There was no remarkable difference in soybean yield, soybean protein, and lipid between selenium and control. The selenium-enriched protein derived from selenium-enriched soybean could be used as a functional ingredient and soybean okra as a selenium-enriched feed for animals for increasing selenium intake.     

Interaction of Protein Particles with Lipids in Soybean Milk

The protein in soybean milk exists as 11S and 7S globulins, and the particles formed from them. The lipid content and composition in the protein fractions and effects of defatting on the form of the protein particles were investigated. The size-distribution of protein particles in both raw and heated soybean milk (soymilk) was not influenced by defatting with hexane, but the number of large particles were slightly increased. The protein particles from raw and heated soymilk samples contained 60% and 3% of the total lipid, respectively. Almost all neutral lipid in the particles of raw soymilk was moved to a floating fraction by heating, but a half of the phospholipids was retained in the particles. The protein components from the hexane-defatted meal were similar to those from whole meal, but those from the C-M-de-fatted meal contained remarkably little β-conglycinin. C-M-de-fatting (Removal of polar lipids) caused a reduction in the particulate fraction, and the addition of phospholipids (lecithin) promoted the formation of protein particles.     

Enzymes of ammonia assimilation in legume nodules: A comparison between ureide- and amide-transporting plants

Levels of amide and ureide biogenic enzymes were compared in the plant cytosol fractions of root nodules from soybean ( Glycine max L. Merr., cv. Williams), pintobean ( Phaseolus vulgaris L. cv. Pinto) and Lupin ( Lupinus angustifolius L. cv. Frost). Enzymes of purine oxidation were found to be present in significant quantities only in ureide-transporting pintobean and soybean nodules. The levels of these enzymes were low in lupin, but this amide-exporter had significantly higher levels of asparagine synthetase. Enzymes of de novo purine biosynthesis and glycine biosynthesis were present at higher levels in pintobean and soybean, consistent with a role for de novo purine biosynthesis in ureide biogenesis. The low levels of these enzymes in lupin are consistent with a role in general purine and amino acid metabolism in these nodules, not directly related to the synthesis of transport compounds for fixed atmospheric nitrogen. Amino acid concentrations in soybean, pintobean and lupin nodules reflected the metabolic differences between amide and ureide plants. The comparative data presented are consistent with a pathway of ureide biogenesis using glutamine, glutamate and aspartate synthesized via reactions catalyzed by glutamine synthetase, glutamate synthase and aspartate aminotransferase in the de novo synthesis of purines followed by oxidation of these purines to produce the ureides allantoin and allantoic acid.     

Microencapsulation of Linoleic Acid with Low- and High-molecular-weight Components of Soluble Soybean Polysaccharide and Its Oxidation Process

Soluble soybean polysaccharide (SSPS) was fractionated into its low- (LMW) and high-molecular-weight (HMW) components to test their antioxidative and emulsifying properties. Linoleic acid was emulsified with an aqueous solution of SSPS, HMW, a mixture of LMW or HMW with maltodextrin, or maltodextrin alone. The emulsions prepared with SSPS, HWM and the mixture of HMW with maltodextrin were stable. These emulsions were spay-dried to produce microcapsules. The encapsulated linoleic acid was oxidized at 37°C and at various levels of relative humidity. Linoleic acid encapsulated with the mixture of LMW with maltodextrin or HMW was stable to oxidation, and this stability increased as the weight fraction of LMW in the mixture was increased. The LMW components also had high DPPH-radical scavenging activity. These results indicate that LMW played an important role in suppressing or retarding the oxidation of linoleic acid encapsulated with SSPS. The oxidative stability of linoleic acid encapsulated with a mixture of the LMW and HMW components was high at low and high relative humidity, but not at intermediate levels of relative humidity.     

Does urinary taurine reflect changes in protein metabolism? A study with cycloheximide in rats

Abstract

We have previously reported on the changes in urinary taurine levels in rats following treatment with some hepatotoxic agents and compounds reported to affect protein synthesis. This study follows the time course of the elevation of urinary taurine after treatment of rats with cycloheximide which was maximal 8–12 h alter dosing and was dose related. [³H]-leucine incorporation into proteins was used as an indicator of protein synthesis. There was a significant reduction in [³H]-leucine incorporation into acid precipitable proteins 8 h but not 24 h after dosing. The reduction in incorporation was negatively correlated with the raised levels of both serum and urinary taurine 8 h after dosing. Liver glutathione was raised both 8 and 24 h after dosing rats and liver taurine was significantly reduced at 8 h. It is suggested that measuring urinary taurine in collections made continuously might provide a simple, non-invasive biomarker for monitoring the effects of xenobiotics or other external stimuli on the status of protein synthesis.     

Use of total dietary fiber across four lemur species (Propithecus verreauxi coquereli,Hapalemur griseus griseus,Varecia variegata,and Eulemur fulvus): Does fiber type affect digestive efficiency?

In vivo digestibility and transit of two experimental diets were compared across four lemur species for which gastrointestinal morphology and preliminary data on physiology differ:Varecia variegata (VV), Eulemur fulvus (EF), Propithecus verreauxi (PV), and Hapalemur griseus (HG). Since free-ranging groups consume varied amounts of slowly fermentable insoluble fiber (IF) and rapidly fermentable soluble fiber (SF), differences in digestibility may be related to variation in the fiber types consumed. To investigate this, two diets were designed to provide 28% of dry matter (DM) as total dietary fiber (TDF). The ratio of IF/SF (g/g) differed across the diets (12.15:1 for the IF diet, and 3.76:1 for the IF/SF diet). The DM digestibility (DMD) of both diets differed across species: DMD was lower for EF and VV (approximately 56-58%), and higher for PV (72%) and HG (76%). The fiber digestibility results were as follows: TDF digestibility was similar for VV and EF (23% and 28%), higher for PV (56%), and highest for HG (66%). IF digestibility was lower for VV and EF (20% and 28%), and higher for PV and HG (53% and 62%). The transit times (TTs) of the two markers Cr and Co were similar (approximately 3.5 hr for VV and EF, 25 hr for PV, and 30 hr for HG). The mean retention times (MRTs) showed the same trend. The results from these captive groups suggest there are large differences in digestive efficiency that are likely related to the varied fiber composition of the free-ranging diet, and the amount of time the digesta are retained in the gut.     

Physiological Effects of Water-soluble Soybean Fiber in Rats

Four-week-old rats were fed on diets containing either no dietary fiber (DF) or a DF source (WSSF, ISF or cellulose) for 4 weeks. The DF level was adjusted to 5%. The WSSF diet contained 3% and 2%, respectively, of WSSF and cellulose. No rat in any group experienced diarrhea, and none of the experimental diets suppressed the growth of rats, the apparent absorption of major nutrients being almost 100%. However, the rate of degradation of DF during the digestive process was significantly different (p<0.05, cellulose, 23.6%; WSSF with cellulose, 64.5% (WSSF degradation only was 91.8%); and ISF, 77.6%). The plasma and liver lipid levels were within normal ranges, although the liver cholesterol level in those rats fed on WSSF and ISF was significantly lower (p<0.05) than in those fed on cellulose. The cecal organic acid contents were in the order of WSSF>ISF>cellulose>DF-free. Furthermore, WSSF was effective in shortening the gastrointestinal transit time. The results indicate that WSSF seems to have favorable effects on the intestinal functions.