陕西3种蝮蛇血清及酯酶同工酶研究

采用聚丙烯酰胺聚胶电泳研究了陕西境内3种蝮蛇：日本蝮短尾亚种（Agkistrodon blomhof-fii brevicaudus）、秦岭蝮（A.qinlingensis）及中介蝮（A.intermedius）的血清及酯酶同工酶。结果表明,3种蝮蛇的血清及酯酶图谱显示一定程度的共性,又存在明显差异,支持形态学将其划分为3个独立种的观点;秦岭蝮与中蛤蝮之间的亲缘关系较近,与日本蝮间的亲缘关系较远。     

纤维素固定化葡萄糖氧化酶的研究

用高碘酸钠（NaIO4)溶液将棉纤维素氧化成氧化纤维素,并将其作为载体使葡萄糖氧化酶能够固定化。考察了溶液的pH值、氧化时间、温度和氧化剂浓度等氧化条件对氧化纤维素醛基含量的影响,优化了氧化条件,研究了固定化葡萄糖氧化酶的活性,借助傅里叶红外光谱和酸－碱滴定法等手段,探讨了葡萄糖氧化酶的固定化机理。研究结果表明,纤维素固定化葡萄糖氧化酶具有较高的生物活性。     

环磷酰胺对小鼠酯酶同工酶的影响及寿胎丸的拮抗作用

用聚丙烯酰胺凝胶电泳的方法研究了雌、雄小鼠（昆明种）7种组织的酯酶（Est）同工酶的变异,环磷酰胺（CTX）对各组织Est同工酶的影响,以及寿胎丸（FPP）的拮抗作用,结果表明：1）各种组织间Est同工酶带型差异明显,并存在一定的性别差异;2）CTX可导致小鼠Est同工酶性显著变化,并且、雄小鼠间舌、脾及肌肉组织受CTX影响的差异显著;3）本研究中CTX造成的Est同工酶变化大都体现在酶的相对量（活性）上,没有发现新酶带的出现;4）FPP对CTX对Est同工酶的影响有十分明显的拮抗作用。     

橡椀单宁降解酶特性的研究

借助于没食子酸丙酯为模型化合物作为底物,对一株能抵抗橡椀单宁(鞣花类单宁)生物毒性并能有效降解这种单宁的菌株的降解特性进行了研究。结果表明这株菌不仅具有单宁酶的活性,而且具有多酚氧化酶（PPO）的活性。通过对不同底物对内胞霉PPO酶促反应速度的影响研究证实橡椀单宁的降解不仅与单宁酶有关还与多酚氧化酶有关。     

Improving the thermal stability of lactate oxidase by directed evolution

Lactate oxidase is used in biosensors to measure the concentration of lactate in the blood and other body fluids. Increasing the thermostability of lactate oxidase can significantly prolong the lifetime of these biosensors. We have previously obtained a variant of lactate oxidase from Aerococcus viridans with two mutations (E160G/V198I) that is significantly more thermostable than the wild-type enzyme. Here we have attempted to further improve the thermostability of E160G/V198I lactate oxidase using directed evolution. We made a mutant lactate oxidase gene library by applying error-prone PCR and DNA shuffling, and screened for thermostable mutant lactate oxidase using a plate-based assay. After three rounds of screening we obtained a thermostable mutant lactate oxidase, which has six mutations (E160G/V198I/G36S/T103S/A232S/F277Y). The half-life of this lactate oxidase at 70 °C was about 2 times that of E160G/V198I and about 36 times that of the wild-type enzyme. The amino acid mutation process suggests that the combined neutral mutations are important in protein evolution. Received 15 September 2006; received after revision 21 October 2006; accepted 2 November 2006     

Inhibitory Kinetics of p-Substituted Benzaldehydes on Polyphenol Oxidase from the Fifth Instar of Pieris Rapae L.

Polyphenol oxidase (PPO) is the enzyme responsible for enzymatic browning during the growth of insects. It is also involved in defense reactions and is related with immunities in insects. PPO, a metalloenzyme oxidase, catalyzes the oxidation of ο-diphenol to ο-quinone. The present paper de- scribes the effects of benzaldehyde and its p-substituted derivatives on the activity of PPO from the fifth instar of Pieris rapae L. PPO from the fifth instar of Pieris rapae L. was purified using ammonium sulfate fractionation and chromatography on Sephadex G-100. The enzyme kinetics was characterized using L-3,4-dihydroxyphenylalanine (L-DOPA) as substrate. The results show that benzaldehyde, p- hydroxybenzaldehyde, p-chlorobenzaldehyde, and p-cyanobenzaldehyde can inhibit the PPO activity for the oxidation of L-DOPA. The inhibitor concentration leading to 50% activity lost, IC50, was esti- mated to be 5.90, 5.62, 2.83, and 2.91 mmol/L for the four tested inhibitors, respectively. Kinetic analy- ses show that the inhibitory effects of these compounds are reversible. Benzaldehyde, p- hydroxybenzaldehyde, and p-chlorobenzaldehyde are noncompetitive inhibitors while p-cyano- benzaldehyde is a mixed-type inhibitor. The inhibition constants were determined for all four inhibitors. p-chlorobenzaldehyde and p-cyanobenzaldehyde were more potent inhibitors than the other com- pounds. These results provide a basis for developing PPO inhibition-based pesticides.     

磁场对小麦种子萌发的生理效应

经过500Gs—3000Gs磁场处理的冬小麦种子,发芽势和发芽率都有增加,其中发芽势增加幅度大于发芽率。在500Gs—2500Gs磁场范围内小麦幼苗的呼吸速率和淀粉酶活力随着场强增大而上升,呼吸速率和淀粉酶活方具有相同的变化模式。胚根内过氧化物酶比胚芽内过氧化物酶对磁场的反应敏感,在2500Gs磁场强度下,胚根过氧化物酶活力比对照增加约1倍,胚芽过氧化物酶活力比对照增加30％,并且有过氧化物同工酶新酶带出现。本实验证实了适当强度磁场对小麦种子萌发的促进作用;过氧化物酶的多重生理功能与其同工酶体系的多型现象有关。     

赤点石斑鱼4种同工酶的组织分布及基因位点分析

运用聚丙烯酰胺垂直梯度凝胶电泳法对赤点石斑鱼7组织(肌肉、肝脏、肾脏、心肌、脑、脾脏、性腺)的4种同工酶(EST、LDH、MDH、ME)进行了初步研究,并对4种酶的同工酶位点及酶谱表型进行了分析.结果表明:赤点石斑鱼的4种同工酶系统具有明显的组织特异性;EST由4个基因位点编码;LDH酶带多于典型的5条酶带;MDH具有线粒体型(m-MDH)和上清液型(s-MDH)两种类型;7种组织只检测到一种类型的ME.     

光敏核不育杂交稻种子纯度的研究

本文利用等电点聚焦电泳测定酯酶同工酶以鉴定光敏核不育种子纯度;胚芽的酯酶同工酶谱能真实地显现该品种的特征,用作种子的鉴定材料为好;Ks-9/T370为互补型同工酶谱,而W6154/特青为杂种型酶谱;严重劣变的种子,在等电点聚焦电泳下,仍能保持该品种特征的酯酶同工酶谱。     

真菌诱导物对丹参毛状根氧化酶活性的影响

从一种广谱病原真菌－大丽轮枝菌的菌丝体中制备激发子,用该激发子和商品生物制剂－酵母提取物分别诱导对数生长期的丹参毛状根,发现丹参毛状根过氧化物酶（POD）,过氧化氢酶（CAT）和多酚氧化酶（PPO）活性在诱导后均显著增加,三种酶的活性并随诱导时间和诱导剂的浓度的增加而改变,大丽轮枝菌激发子的作用强于酵母提取物,表现为诱导酶活性峰值较高和峰值时间提前。