NADH oxidase from the extreme thermophile Thermus aquaticus YT‐1

Open Access
Publisher Website
Google Scholar
Abstract
A protein with NADH oxidase activity form 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 compositon as the NADH oxidase isolated from the mesophile Bacillus megaterium. Purified NADH oxidase was found to have a Km of 39 .mu.M for .beta.-NADH and a Vmax of 4.68 .mu.mol NADH mg-1 min-1 and was still active at 95.degree.C. Enzymatic activity was found to be independent of pH between 5.0 and 10.5.