奥利弗·史密斯

对于遗传学而言,一项最根本的任务是研究特定基因的功能,20世纪70年代基因工程的出现促进了该方面的研究,而80年代基因剔除(又称基因打靶)技术的发明则更加快了研究者对基因功能的理解,今天基因剔除小鼠已经成为研究人类多种疾病如癌症、糖尿病和动脉硬化等的模型,是分子遗传学的必备材料.     

Three Metabolites Produced by Valsa sp.

Two enzymes, nitrile hydratase and amidase, which participate in the conversion of trans-1,4- dicyanocyclohexane (t-DCC) to frans-4-cyanocyclohexane-l-carboxylic acid (t-MCC), a tranexamic acid intermediate, were purified and characterized. Nitrile hydratase was obtained in a homogeneous state. The molecular weight of the native enzyme was 61,400 and that of the subunit 26.900, indicating a dimer structure. Valeronitrile and butyronitrile were good substrates for the enzyme. The enzyme could also hydrate benzonitrile, p-hydroxybenzonitrile and 4-cyanobenzoic acid. t-DCC was ex-clusively hydrated to fnzws-4-cyanocycIohexane-l-car boxy amide (t-MCMA), further hydration of the nitrile group of t-MCMA and t-MCC not being observed. The presence of pyrroloquinoline quinone in the enzyme was confirmed. The presence of iron was also confirmed. The amidase of the strain was also purified. The latter enzyme could hydrate t-MCMA, yielding t-MCC. The enzyme was highly resistant to SH reagents.