壳寡糖对烟草TMV病毒的诱导抗性研究

以壳寡糖诱导烟草枯斑寄主后，调查了病班的抑制率，同时研究了壳寡糖单独处理和以病毒粒子侵染诱导的病程相关蛋白的差异，壳寡糖处理对TMV侵染有保护作用，施用壳寡糖后7d，以浓度为50ug/mL和75ug/mL对枯斑的抑制效果为好，壳寡糖在活体外对TMV粒子有钝化作用，单独施用壳寡糖可以诱导烟草产生6条耐碱性的PR，其中1条区别于TMV侵染诱导的PR。     

胶原蛋白酶解产物功能特性研究

本文研究了胶原蛋白经酶水解后所得胶原水解物的功能特性。酶解后胶原蛋白分子量减小，胶原酶解产物的吸水性、保水性、溶解性较酶解前都得到提高，但是吸油性、起泡性和泡沫稳定性都明显下降。对胶原蛋白进行有限水解，使其功能特性发生改变，有利于其在化妆品以及食品添加剂等方面的应用。     

蜂王浆中水溶性蛋白质和活性肽的研究进展

蜂王浆中的蛋白质和肽对蜂王浆的生理活性有重要影响。综述了近年来蜂王浆水溶性蛋白和活性肽的分离纯化、蛋白质结构，以及功能特性等方面的研究状况。     

Antioxidant activities of crude tea polyphenols, polysaccharides and proteins of selenium-enriched tea and regular green tea

The crude tea polyphenols, polysaccharides and proteins of regular green tea and Se-enriched green tea were investigated in vitro for antioxidant activities by auto-oxidation test (AAPH) and α,α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging method. Results showed that crude tea polyphenols of Se-enriched green tea provided the highest antioxidant activity by DPPH assay and the antioxidant activity was decreased in the order: crude tea polyphenols > crude tea proteins > tea polysaccharides. The crude protein of Se-enriched green tea was found to exhibit the highest antioxidant activity by AAPH method and the antioxidant activity was decreased in the order: crude tea proteins > tea polyphenols > tea polysaccharides. Tea polyphenols and tea polysaccharides of Se-enriched green tea presented significantly higher antioxidant activities than that of regular green tea. No significant difference of antioxidant activities was found between crude tea proteins of Se-enriched green tea and regular green tea. The combinations of Se with tea polyphenols and tea polysaccharides were responsible for the higher antioxidant activities of Se-enriched green tea than regular green tea.     

大豆7S和11S球蛋白的结构和功能性质

主要介绍大豆７Ｓ和１１Ｓ球蛋白的结构和功能性质，大豆蛋白质各个成分的分子量有所不同，按超速离心分离系数可分为２Ｓ，７Ｓ１１Ｓ和１５Ｓ４个组份。７Ｓ组份占总蛋白质的３０．９％，它是由４种不同大豆蛋白民组成，１１Ｓ组份占总大豆蛋白质的４１％，而且都是单一的１１Ｓ球蛋白，１１Ｓ球蛋白的等电点为ｐＨ４．６４。     

Rheological properties of gluten derived from wheat cultivars with identical HMW glutenin subunit composition†

Ten spring wheat cultivars possessing identical HMW glutenin subunits (2*, 7+8, 5+10) were evaluated for gluten and protein content. Gluten content was related to flour protein content (r=0·98). Addition of freeze-dried gluten to the base flour (cv Alpha) to a constant protein level of 12% generally increased dough strength. However, the magnitude of variation in mixing patterns depended more on the type of the supplemental gluten. Fortification of the base flour with the freeze-dried gluten from the cv Glenlea produced mixographs with the longest mixing development time (MDT), and highest band width energy (BWE) and energy to peak (ETP), suggesting that the source of gluten had a strong effect on dough rheology. The viscoelastic properties of undiluted wet gluten varied between cultivars during mixing reflecting differences in gluten quality. Freshly prepared wet gluten of Glenlea showed extended mixing tolerance as compared to Norseman or Alpha gluten. The wet gluten from cv Glenlea was less extensible with high maximum resistance to extension and had a larger area under the extensigraph curve than gluten obtained from cv Norseman. Gluten prepared from the cultivars Glenlea, Bluesky and Wildcat were less soluble in aqueous propanol and produced more froth when the dough was washed with deionised water. The froth proteins, separated by SDS-PAGE, predominantly contained strongly stained bands in the region corresponding to molecular weight <50 kDa. The rapid tests such as froth formation and alcohol solubility used in this study to discriminate various glutens were highly correlated with the mixograph parameters. These methods can be of practical value in evaluating gluten quality. © 1998 Society of Chemical Industry.     

Effect of lipid oxidation and frozen storage on muscle proteins of Atlantic mackerel (Scomber scombrus)

The effect of storage on the lipids and proteins in Atlantic mackerel stored for up to 24 months at ?20 and ?30 °C was studied. Traditional methods including the peroxide value, thiobarbituric acid‐reactive substances (TBARS) and a reverse phase HPLC method were used to determine the primary and secondary lipid oxidation products. All tests showed an increase in lipid oxidation products with storage time and at a higher storage temperature of ?20 °C compared with samples stored at ?30 °C. Antioxidants had a significant effect (P < 0.01) on the inhibition of lipid oxidation, as shown by the reduction in peroxide value and hydroxides, and malondialdehyde formation. Similarly, deterioration of protein structure and functionality in mackerel stored for 3, 6, 12 and 24 months was greater at ?20 than ?30 °C. ATPase activity in the myosin extract of Atlantic mackerel showed a significant decrease (P < 0.01) with progressive frozen storage. Protein solubility in high salt concentration (0.6 M NaCl) decreased (P < 0.01) during storage at both ?20 and ?30 °C but was greater at ?20 °C. Interestingly, antioxidants BHT, vitamin C and vitamin E protected the proteins against complete loss of ATPase activity and protein solubility to a significant level (P < 0.01) for up to 1 year at ?20 °C compared with samples stored without antioxidants. This study confirms the deleterious effect of lipid oxidation products on protein structure and function in frozen fatty fish. © 2002 Society of Chemical Industry     

MTGase聚合大豆蛋白及其改性机理(III) MTGase聚合改性大豆蛋白机理

采用紫外光谱 (UV -spectrum)、荧光光谱 (fluorescencespectrum)以及红外光谱 (FT -IRspectrum)分析了SAPP以及其MTGase -聚合物的结构特征。紫外光谱结果显示MTGase催化SAPP导致它的多肽链的侧链结构发生了变化 ,Tyr和Trp残基的吸收峰红移说明其Cα原子的构型从非平面型转变为平面型 ,而荧光光谱显示MTGase催化导致SAPP的疏水区域暴露出来 ,而且还经历一个空间结构重排的过程 ,而红外光谱显示这种聚合作用还导致多肽链的二级结构发生较大的变化 ,即一部分的 β -折叠二级结构转变为以α -螺旋或无规卷曲。从蛋白质分子结构的角度 ,探讨了MTGase聚合SAPP的改性机理 ,指出其机理在于MTGase聚合导致了SAPP的空间结构发生了变化的缘故。     

Evaluation of the peptide profile with a view to authenticating buffalo mozzarella cheese

Electrophoretic and chromatographic techniques were used to determine water‐soluble peptide profiles aiming to identify the adulteration of buffalo milk mozzarella cheese by the addition of cow's milk. Thus, cheeses were produced with contents of cow's milk varying from 0% to 100%, and the peptides extracted after production and after 20 days of refrigeration. Polyacrylamide gel electrophoresis under denaturing conditions in the presence of sodium dodecyl sulphate (SDS‐PAGE) identified a potential peptide marker of exclusively bovine origin with a size of about 21 kDa for the addition of cow's milk above 30%. Reverse‐phase high‐performance liquid chromatography (RP‐HPLC) indicated the existence of two potential peptides present in higher concentrations in buffalo milk and one exclusive for cow's milk, the latter making it possible to estimate the addition of cow's milk to buffalo milk. Six commercial brands of buffalo mozzarella cheese were evaluated, and indications of adulteration found in four of them.     

MTGase聚合大豆蛋白及其改性机理(I)MTGase催化大豆蛋白研究

采用SDS-PAGE结合凝胶扫描技术，研究了微生物转谷氨酰胺酶(MTGase)对大豆酸沉蛋白(SAPP)的聚合作用，以及不同酶量、加热或蛋白酶预处理对该聚合反应的影响。结果显示：(1)MTGase较易催化SAPP的大豆球蛋白(glycinin)聚合，而不易使7S球蛋白聚合，而且只能使大豆球蛋白中的酸性亚基聚合，几乎不能使其碱性亚基聚合；(2)随着酶量的增加，MTGase对大豆球蛋白的聚合效果逐渐递增，10～20U／g酶量范围内的聚合效果差不多；(3)加热预处理(100℃，O～45s)可显著地提高MTGase对SAPP的聚合效果；(4)适度的蛋白酶降解处理有利于MTGase对SAPP的聚合，而深度的蛋白酶降解处理则不利。