Antonie van Leeuwenhoek

, Volume 52, Issue 5, pp 387–392 | Cite as

The apparent oxidation of NADH by whole cells of the methylotrophic bacterium Methylophilus methylotrophus

A cautionary tale
  • R. A. Patchett
  • C. W. Jones
Article

Abstract

Previous reports that whole cells of Methylophilus methylotrophus oxidase exogenous NADH have been investigated. Essentially identical rates of oxygen consumption were observed following the addition of methanol or NADH to whole cells. Both activities were inhibited by EDTA and hydroxylamine, but not by HQNO, and exhibited similar pH optima. Analyses of the reaction stoichiometry with NADH as substrate showed that the expected amount of oxygen was consumed, but also revealed acidification (instead of alkalinisation) and no oxidation of NADH. Further studies showed that commerical NADH is contaminated with ethanol which is oxidised to acetic acid by the low specificity methanol oxidase system present in this organism. The oxidation of exogenous NADH by whole cells of M. methylotrophus reported previously is therefore spurious.

Key words

Methylophilus methylotrophus NADH oxidation Methanol oxidase 

Abbreviations

EDTA =

ethylenediaminetetracetate

HQNO =

2−n-heptyl-4-hydroxy-quinoline-N-oxide

DEAE =

diethylaminoethyl

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Copyright information

© Martinus Nijhoff Publishers 1986

Authors and Affiliations

  • R. A. Patchett
    • 1
  • C. W. Jones
    • 1
  1. 1.Department of BiochemistryUniversity of LeicesterLeicesterUK

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