糖蜜发酵过程中乙醇脱氢酶对发酵效率的影响

在用糖蜜为原料的酒精发酵生产过程中,通过气象色谱仪测出发酵环境中有大量乙醛的存在,同时酒精浓度也一直偏低.于是通过对发酵温度,pH和去除金属离子等因素做出调整,研究乙醇脱氢酶对发酵结果的影响.结果表明乙醇脱氢酶活性会对发酵效率产生影响.     

Chaperone-like features of bovine serum albumin: a comparison with α-crystallin

The chaperone behaviour of bovine serum albumin was compared with that of α-crystallin. The chaperone activity was assessed by measuring: (i) the ability to antagonize protein aggregation induced by heat; (ii) the capability to protect the activity of thermally stressed enzymes and (iii) the effectiveness in assisting the functional recovery of chemically denatured sorbitol dehydrogenase. Despite the lack of structural analogies, both proteins show several functional similarities in preventing inactivation of thermally stressed enzymes and in reactivating chemically denatured sorbitol dehydrogenase. As with α-crystallin, the chaperone action of bovine serum albumin appears to be ATP independent. Bovine serum albumin appears significantly less effective than α-crystallin only in preventing thermally induced protein aggregation. A possible relationship between chaperone function and structural organization is proposed. Together, our results indicate that bovine serum albumin acts as a molecular chaperone and that, for its particular distribution, can be included in the extracellular chaperone family. Received 29 August 2005; received after revision 23 September 2005; accepted 12 October 2005     

Alpha-crystallin: an ATP-independent complete molecular chaperone toward sorbitol dehydrogenase

-Crystallin, the major component of the vertebrate lens, is known to interact with proteins undergoing denaturation and to protect them from aggregation phenomena. Bovine lens sorbitol dehydrogenase (SDH) was previously shown to be completely protected by -crystallin from thermally induced aggregation and inactivation. Here we report that -crystallin, in the presence of the SDH pyridine cofactor NAD(H), can exert a remarkable chaperone action by favoring the recovery of the enzyme activity from chemically denaturated SDH up to 77%. Indeed, even in the absence of the cofactor, -crystallin present at a ratio with SDH of 20:1 (w:w) allows a recovery of 35% of the enzyme activity. The effect of ATP in enhancing -crystallin-promoted SDH renaturation appears to be both nonspecific and to not involve hydrolysis phenomena, thus confirming that the chaperone action of -crystallin is not dependent on ATP as energy donor.Received 28 October 2004; received after revision 22 December 2004; accepted 10 January 2005     

Single amino acid substitutions insn-glycerol-3-phosphate dehydrogenase allozymes fromDrosophila virilis

Summary The amino acid sequence was compared among the three allelic variants (allozymes) ofsn-glycerol-3-phosphate dehydrogenase inD. virilis, which are detected by one-dimensional electrophoresis. The GPDH^f variant was different from the GPDH^m by only one substitution of 68-lysine for asparagine; GPDH^s differed from GPDH^m by substitution of 127-glycine for arginine. No electrophoretically silent substitutions were found in a total of 352 amino acid residues.     

聚丙烯酰胺凝胶上SDH的活染

粗心选择了电泳系统及活染条件，得到较清晰的活染结果，从活染胶析 米叶ＳＤ途中 形式，而根部只有一种形式，可能在叶及根部都存在的那种ＳＤＨ形式具有更重要的生理意义。     

Alcohol dehydrogenase activity in cultured cells from different tobacco (Nicotiana tabacum L.) varieties

The activity of alcohol dehydrogenase (ADH) in cultured cells of various tobacco was determined. It was found that significant differences existed in cells of different varieties cultured under normal conditions and as well after treated with exogenous ethanol. The ADH activity had positive relation with the ability of the cells to catabolize exogenous ethanol, indicating that the main function of the ADH in tobacco cells was in the direction of converting ethanol to acetaldehyde. Foundation item: Supported by the Natural Science Foundation of Guandong Province. (No. 950406) Biography: Zheng ling (1974-), female, Master student.     

Synergistic effects of cellobiose dehydrogenase and manganese-dependent peroxidases during lignin degradation

The synergistic effects of cellobiose dehydrogenase (CDH) and manganese-dependent peroxidases (MnP) on the degradation of kraft pulp cellulolytic enzyme lignin (CEL) were investigated. Addition of CDH significantly increased the amount of water-soluble products reduced from CEL by MnP. CDH facilitated the reduction of the contents of methoxyl, carboxyl, phenolic hydroxyl and total hydroxyl groups of CEL by MnP.¹H-NMR analysis showed that addition of CDH also decreased further the amount of protons of CEL degraded by MnP. The results proved for the first time that CDH could promote degradation of lignin by MnP and suggest that CDH could not only promote degradation of cellulose but also is an important part of the lignin biodegradation system.     

牡蛎提取物对运动大鼠血清和骨骼肌LDH活性及LA的影响

目的：探讨灌喂牡蛎提取物对大强度运动训练大鼠运动能力与血清和骨骼肌LDH活性及LA含量的影响．方法：实验动物随机分为对照组、运动组、牡蛎＋运动组（牡蛎组）,每组10只．对照组不进行运动训练,其余两组大鼠进行游泳训练,每周训练6天,共9周．9周后检测大鼠力竭游泳时间、血清和骨骼肌LDH活性及LA含量．结果：牡蛎提取物能明显提高大鼠运动能力,延长力竭时间,与运动组比较呈显著性差异（P〈0．05）．牡蛎组大鼠血清LDH活性和BLA含量均低于运动组,而骨骼肌LDH活性高于运动组,但LA也低于运动组（P〈0．05）．对照组大鼠血清和骨骼肌LDH活性和LA含量与牡蛎组比较均无显著差异（P〉0．05）．运动组大鼠血清和骨骼肌的LA含量均高于对照组和牡蛎组（P〈0．05）;运动组大鼠血清LDH活性高于对照组和牡蛎组,而骨骼肌LDH活性低于对照组和牡蛎组（P〈0．05）．结论：灌喂牡蛎提取物能提高大鼠的运动能力,具有较好的抗疲劳效果．     

Inactivation and Conformational Changes of Lactate Dehydrogenase M4 during Unfolding in Urea Solutions

ＩｎａｃｔｉｖａｔｉｏｎａｎｄＣｏｎｆｏｒｍａｔｉｏｎａｌＣｈａｎｇｅｓｏｆＬａｃｔａｔｅＤｅｈｙｄｒｏｇｅｎａｓｅＭ４ｄｕｒｉｎｇＵｎｆｏｌｄｉｎｇｉｎＵｒｅａＳｏｌｕｔｉｏｎｓＧｕｏＹｕｙｕａｎ（郭宇远），ＺｈｏｕＨａｉｍｅｎｇ（周海梦）＊Ｄｅｐ...     

丙酮酸脱氢酶复合体的研究进展及应用

综述了丙酮酸脱氢酶复合体（PDHc）的组成、结构功能、调控机制、缺陷疾病及在医学和农业中的应用.丙酸酸脱氢酶系是定位在线粒体中的多酶复合体,它是由丙酮酸脱氢酶（E1）、二氢硫辛酸乙酰转移酶（E2）、二氢硫辛酸脱氢酶（E3）和一些辅助因子组成.高等生物中PDHc活性的调节主要是通过对其E1的磷酸化和去磷酸化来实现的,而细菌的PDHc的活性主要是通过别构效应来调节,PDHc缺陷导致代谢障碍,组织受损.