粗糙脉孢菌线粒体DNA拓扑异构酶I的特性分析

Characterization of mitochondrial DNA topoisomerase I from Neurospora crassa.

作者信息

Turna J, Pudzisová A, Osuský M, Supeková L, Kuchta T

机构信息

Department of Molecular Biology, Faculty of Science, Comenius University, Bratislava, Slovakia.

出版信息

Folia Microbiol (Praha). 1994;39(2):105-11. doi: 10.1007/BF02906803.

DOI:10.1007/BF02906803

PMID:7959426

Abstract

DNA topoisomerase I isolated from the lower eukaryote Neurospora crassa mitochondria was characterized. Molar mass of the enzyme in the native state is 120 kDa and 60-65 kDa when denatured. The pH optimum of the enzyme is 7.8 and the KCl optimum concentration is 40 mmol/L. This topoisomerase is independent of ATP and Mg2+. N-Ethylmaleimide, 4-chloromercuribenzoate, SDS, guanidinium chloride, polyethylene glycol, heparin and ethidium bromide inhibit its activity, while novobiocin, nalidixic acid, Triton X-100 and chloroquine do not. Polyamines and histone H1 stimulate the topoisomerase activity. We classify this DNA topoisomerase as type I and eukaryotic. Conversion of the topoisomerase to a nonspecific endonuclease at increased temperature is proposed.

摘要

对从低等真核生物粗糙脉孢菌线粒体中分离出的DNA拓扑异构酶I进行了表征。该酶天然状态下的摩尔质量为120 kDa，变性时为60 - 65 kDa。该酶的最适pH为7.8，最适KCl浓度为40 mmol/L。这种拓扑异构酶不依赖ATP和Mg2+。N - 乙基马来酰亚胺、4 - 氯汞苯甲酸、SDS、氯化胍、聚乙二醇、肝素和溴化乙锭会抑制其活性，而新生霉素、萘啶酸、曲拉通X - 100和氯喹则不会。多胺和组蛋白H1会刺激拓扑异构酶的活性。我们将这种DNA拓扑异构酶归类为I型且为真核生物的。有人提出在温度升高时该拓扑异构酶会转变为非特异性核酸内切酶。