Crotonobetaine Reductase From Escherichia Coli--A New Inducible Enzyme of Anaerobic Metabolization of L(-)-carnitine

Antonie Van Leeuwenhoek. 1994;65(1):63-9. doi: 10.1007/BF00878280.

Abstract

Crotonobetaine reductase from Escherichia coli 044 K74 is an inducible enzyme detectable only in cells grown anaerobically in the presence of L(-)-carnitine or crotonobetaine as inducers. Enzyme activity was not detected in cells cultivated in the presence of inducer plus glucose, nitrate, gamma-butyrobetaine or oxygen, respectively. Fumarate caused an additional stimulation of growth and an increased expression of crotonobetaine reductase. The reaction product, gamma-butyrobetaine, was identified by autoradiography. Crotonobetaine reductase is localized in the cytoplasm, and has been characterized with respect to pH (pH 7.8) and temperature optimum (40-45 degrees C). The Km value for crotonobetaine was determined to be 1.1 x 10(-2M). gamma-Butyrobetaine, D(+)-carnitine and choline are inhibitors of crotonobetaine reduction. For gamma-butyrobetaine (Ki = 3 x 10(-5M)) a competitive inhibition type was determined. Various properties suggest that crotonobetaine reductase is different from other reductases of anaerobic respiration.

MeSH terms

  • Anaerobiosis
  • Carnitine / metabolism*
  • Cell-Free System
  • Escherichia coli / enzymology*
  • Multienzyme Complexes*
  • Oxidoreductases / analysis*

Substances

  • Multienzyme Complexes
  • Oxidoreductases
  • crotonobetaine reductase
  • Carnitine