不同大豆品种11S球蛋白结构特性与表面疏水性关系研究

以6个代表性大豆品种制备11S球蛋白,研究大豆11S球蛋白结构特性与表面疏水性关系。采用ANS荧光探针法测定表面疏水性,Ellman试剂分析法测定巯基和二硫键含量,激光拉曼光谱和荧光光谱分析空间构象。结论表明,大豆11S球蛋白表面疏水性与α-螺旋含量、β-折叠含量负相关,与β-转角含量、无规则卷曲含量正相关;与拉曼光谱色氨酸费米共振I1360/I1340值负相关,与拉曼光谱酪氨酸费米共振I850/I830值正相关,与暴露酪氨酸残基克分子数正相关,与N暴露N包埋值正相关;与暴露巯基含量、巯基暴露程度正相关,与游离巯基含量、二硫键含量、二硫键构象相关性不显著。     

Modification of protein structure and dough rheological properties of wheat flour through superheated steam treatment

Native (NF, 13.5% w.b) and moistened (MF, 27% w.b) wheat flours were treated with superheated steam (SS) at 170 °C for 1, 2 and 4 min, and their protein structure as well as dough rheological properties were analyzed. Confocal laser scanning microscopy (CLSM) and SDS-PAGE patterns indicated the formation of protein aggregates with reduced SDS extractability after treatment. Farinograph and dynamic rheometry measurements showed that the strength as well as elastic and viscous moduli of the dough made from SS-treated flours progressively increased with SS treatment time. And both the improvements were more pronounced for superheated steam-treated moistened flours (SS-MF) than for superheated steam-treated native flours (SS-NF). Size-exclusion high performance liquid chromatography (SE-HPLC) analysis demonstrated that dough rheological parameters have positive correlations with SDS unextractable polymeric proteins (UPP) contents. SS treatment on flours led to a transition of protein secondary structures to more ordered form (α-helix and β-sheet). Additionally, free sulfhydryl (SH) contents decreased after treatment, which implied that disulfide bonds accounted for protein extractability loss and dough rheological properties improvement. Elevated moisture level promoted the modification of both protein structure and dough behaviors of flours during SS treatment.     

Antiradical function of sulfhydryl residues and oxidative stress markers in dairy cattle plasma

The antiradical function of sulfhydryl (SH) residue in dairy cattle plasma and the relationship of SH residue concentrations to other oxidative stress markers, ascorbic acid and thiobarbituric acid reactive substance (TBARS) in plasma were investigated. The concentration of reduced glutathione (GSH) in phosphate buffer solution (pH 7.6) and SH residues in dairy cattle plasma decreased significantly (P < 0.05) in vitro by the addition of peroxyradicals at 38°C, depending on incubation periods. The decrease of GSH concentration with the peroxyradical solution was partially protected by the addition of sodium ascorbate solution. A positive and significant correlation with SH residues and albumin concentration in the fresh plasma obtained from 15 dairy cattle was observed (P < 0.05). The SH residue concentration was not correlated with the TBARS concentration in plasma. The total ascorbic acid and SH residues concentration in the plasma correlated positively but not significantly (P < 0.10). These results suggested that SH residues in dairy cattle plasma play important part in the antiradical function.     

鸡肉蛋白热处理与酶解特性的关系研究

为阐明酶解前热处理对鸡肉蛋白酶解性质的影响，采用差示扫描量热法分析鸡肉蛋白的热性质，研究热处理温度对鸡肉蛋白巯基(SH)、二硫键(S-S)含量以及碱性蛋白酶(Alcalase)、木瓜蛋白酶(Papain)酶解过程中氨基酸、肽释放的影响。结果表明：鸡肉蛋白有4个吸热峰，对应温度为63.7℃、67.6℃、74.3℃和 77.9℃；热处理温度增加，鸡肉蛋白中SH含量逐渐降低，而S-S含量逐渐增加，游离SH与S-S还原折算的SH量之和在80℃前无明显变化，80℃后下降；酶解前热处理不利于鸡肉蛋白酶解过程中游离氨基酸、小分子量肽的释放和可溶性氮的回收，但有利于大分子量肽的生成，因此可根据酶解产物的应用目的选择热处理参数。     

Zinc nutrition effect on the tolerance of wheat genotypes to Fusarium root-rot disease in a solution culture experiment

Abstract

Zinc (Zn) nutrition and plant genotype are two factors that may affect the tolerance of wheat to root-rot diseases. The aim of the present study was to determine the effect of Zn on shoot yield, root permeability and infection by Fusarium solani in six wheat genotypes with different Zn efficiency. A greenhouse (solution culture) experiment was carried out in which five bread wheat genotypes (Triticum aestivum L. cvs Rushan, Kavir, Cross, Pishtaz and Falat) and one durum wheat genotype (Triticum durum L. cv. Yav79), which are common in Zn-deficient soils of Iran and were exposed to two levels of Zn (0 and 1?μmol?L^–1?Zn?kg^?1, as ZnSO₄.7H₂O) and two F. solani infection levels (0 and 10⁶?spore?mL^?1). Zinc deficiency significantly decreased shoot dry matter in five of the genotypes (Yav79, Kavir, Rushan, Cross and Falat), but had no effect on shoot growth in Pishtaz. Infection with F. solani significantly decreased the shoot dry matter in Yav79, but did not affect the shoot dry weight of the other wheat genotypes. Root membrane permeability was lower in the Zn treatments than in the Zn-free treatments. Zinc deficiency caused a decrease in root reactive sulfhydryl (SH) groups, particularly in the Cross genotype. Root sulfhydryl groups decreased with Fusarium infection. Zinc application sharply increased the Zn content and decreased the Mn content of the shoots. Application of Zn had a positive effect on the tolerance of wheat to F. solani root rot. The relationship between Zn nutrition and disease tolerance suggests that Zn deficiency should be treated before evaluating the cost-effectiveness of fungicides. No correlation was found between the Zn efficiency of the wheat genotypes and Fusarium root-rot disease severity in this solution culture experiment.     

转谷氨酰胺酶对小麦面粉加工品质的影响研究

为了改善小麦面粉的加工品质通过面筋蛋白乳酸溶液透光率和膨胀高度的测定探讨小麦面粉中转谷氨酰胺酶最适添加量,研究了转谷氨酰胺酶对面粉中游离巯基含量、面粉持水性、面粉粉质特性和加工品质的影响.结果表明,转谷氨酰胺酶的最适添加量为1.0‰;在其最适添加量下,面粉中游离巯基含量下降,持水性增加,粉质特性以及成品面条、速冻饺子的品质均得到改善.     

Immunomodulatory activities of non-prolamin proteins in wheat germ and gluten

Albumin (Alb), globulin (Glo), glutelin (Gll) and glutenin (Gln) were separately extracted from wheat germ and wheat gluten. Amino acisd composition, molecular weight distribution, solubility, in vitro digestibility, and immunomodulatory activities were all analyzed. Gll and Gln have similar molecular weight distributions, which differed from those of Alb and Glo. Alb showed the highest solubility at various pH values (except pH 4.0), whereas Glo showed the highest in vitro digestibility. Glo and Gll have the highest proportion of essential to total amino acids, while Alb and Gll have the highest protein digestibility-corrected amino acid scores. Gll had the strongest immunomodulatory effects in terms of stimulation of RAW 264.7 cells to produce IL-6, TNF-α, and IL-10, and good stimulatory effects on splenocyte proliferation, production of IL-2, phagocytosis, and secretion of nitric oxide in RAW 264.7 cells. Gll can be considered a good protein source for use in health foods.     

施硫对小麦籽粒形成过程中蛋白质与巯基、二硫键的含量及加工品质的影响

在土壤耕层有效硫含量为728 mg/kg的条件下,选用不同冬小麦品种济麦20、淄麦12、鲁麦21和山农1391为试验材料,研究了施用硫肥对小麦不同穗位和不同粒位子粒蛋白质与巯基、二硫键含量及加工品质的影响。结果表明,施用硫肥对上部穗位粒的蛋白质含量的提高作用大于其他穗位粒; 增加了高蛋白含量品种济麦20和淄麦12 的弱势粒子粒蛋白质含量,增加了上部小穗位子粒和中部穗位强势粒的巯基含量,提高了不同穗位子粒二硫键含量; 而对不同粒位子粒二硫键含量的影响则因品种而异。施用硫肥使小麦面粉湿面筋含量、面团形成时间、稳定时间和粉质评价值均有一定提高,但不同品质指标对施用硫肥的反应存在差异。与子粒形成过程中蛋白质含量的变化相反,巯基的含量变化呈先升后降的规律; 二硫键的含量变化趋势与蛋白质含量的变化相似,但最小值出现时间略有延迟。     

Effects of atropine and pralidoxime pretreatment on serum and cardiac oxidative stress parameters in acute dichlorvos toxicity in rats

Recent several studies have reported that oxidative stress could be an important component of the mechanism of cardiotoxicity due to organophosphate-induced toxicity. The aim of this study is to evaluate the oxidative and antioxidative parameters in cardiac toxicity of organophosphate poisoning, and determine the effects of atropine and pralidoxime on this parameters. The experimental groups were randomly divided into five groups as control (corn oil), dichlorvos (30 mg/kg), atropine (10 mg/kg), pralidoxime (40 mg/kg), and atropine (10 mg/kg) + pralidoxime (40 mg/kg) groups. Serum cholinesterase levels were suppressed with dichlorvos, and these reductions were inhibited with atropine and/or pralidoxime pretreatment. Serum, but not cardiac, total free sulfhydryl groups and paraoxonase activities were significantly increased in the pralidoxime group when compared to the control group. Serum arylesterase activities were elevated in the dichlorvos, atropine, pralidoxime, and atropine + pralidoxime groups when compared to the control group (P < 0.05). Total oxidant status, oxidative stress index, malondialdehyde and catalase activities in serum and cardiac tissues were not markedly different between the groups. No significant changes were also observed with cardiac myeloperoxidase and serum ceruloplasmin activities. In conclusion, these results showed that acute dichlorvos administration did not cause marked cardiac damage, and oxidative stress probably does not play a major role in dichlorvos-induced poisoning. On the other hand, especially pralidoxime treatment markedly increased the serum total free sulfhydryl groups, paraoxonase and arylesterase activities. However, the underlying mechanisms for these changes are not exactly known.     

甲基对硫磷压电免疫传感技术的初步探讨

分别利用蛋白A法和巯基自组装膜法将抗体固定在压电石英晶体金电极上,结果表明巯基自组装膜法效果更好。在利用巯基自组装膜法固定甲基对硫磷抗体的基础上,初步建立了基于直接法和竞争法的甲基对硫磷压电免疫传感技术并对两种技术作了比较,结果表明,基于竞争法的压电免疫传感技术对对硫磷抗原抗体反应的响应频移值较大,可提高检测灵敏度,降低检测限。