嗜热栖热菌YT-1中的NADH氧化酶。纯化与特性鉴定。

NADH oxidase from the extreme thermophile Thermus aquaticus YT-1. Purification and characterisation.

作者信息

Cocco D, Rinaldi A, Savini I, Cooper J M, Bannister J V

机构信息

Institute of Biological Chemistry, Faculties of Pharmacy and Medicine, University of Cagliari, Italy.

出版信息

Eur J Biochem. 1988 Jun 1;174(2):267-71. doi: 10.1111/j.1432-1033.1988.tb14093.x.

DOI:10.1111/j.1432-1033.1988.tb14093.x

PMID:3383846

Abstract

A protein with NADH oxidase activity from the extreme thermophile Thermus aquaticus YT-1 was purified and characterised. The enzyme was found to have a relative molecular mass of 110,000 and be composed of two subunits of identical size. FAD was found to be present at a concentration of 0.7 mol/mol dimer and was required for activity. During the oxidation of NADH, oxygen uptake takes place with the production of hydrogen peroxide. The enzyme had, with the exception of a higher glutamic acid and tryptophan content, a similar amino acid composition as the NADH oxidase isolated from the mesophile Bacillus megaterium. Purified NADH oxidase was found to have a Km of 39 microM for beta-NADH and a Vmax of 4.68 mumol NADH mg-1 min-1 and was still active at 95 degrees C. Enzymatic activity was found to be independent of pH between 5.0 and 10.5.

摘要

对嗜热栖热菌YT-1中一种具有NADH氧化酶活性的蛋白质进行了纯化和表征。发现该酶的相对分子质量为110,000，由两个大小相同的亚基组成。发现FAD以0.7 mol/mol二聚体的浓度存在，且其活性需要FAD。在NADH氧化过程中，会消耗氧气并产生过氧化氢。除谷氨酸和色氨酸含量较高外，该酶的氨基酸组成与从中温菌巨大芽孢杆菌中分离出的NADH氧化酶相似。发现纯化的NADH氧化酶对β-NADH的Km为39 μM，Vmax为4.68 μmol NADH mg-1 min-1，在95℃时仍具有活性。发现酶活性在pH 5.0至10.5之间与pH无关。