Kinetic mechanisms of glycine oxidase from Bacillus subtilis

Eur J Biochem. 2003 Apr;270(7):1474-82. doi: 10.1046/j.1432-1033.2003.03513.x.

Abstract

The kinetic properties of glycine oxidase from Bacillus subtilis were investigated using glycine, sarcosine, and d-proline as substrate. The turnover numbers at saturating substrate and oxygen concentrations were 4.0 s(-1), 4.2 s(-1), and 3.5 s(-1), respectively, with glycine, sarcosine, and D-proline as substrate. Glycine oxidase was converted to a two-electron reduced form upon anaerobic reduction with the individual substrates and its reductive half-reaction was demonstrated to be reversible. The rates of flavin reduction extrapolated to saturating substrate concentration, and under anaerobic conditions, were 166 s(-1), 170 s(-1), and 26 s(-1), respectively, with glycine, sarcosine, and D-proline as substrate. The rate of reoxidation of reduced glycine oxidase with oxygen in the absence of product (extrapolated rate approximately 3 x 10(4) M(-1) x s(-1)) was too slow to account for catalysis and thus reoxidation started from the reduced enzyme:imino acid complex. The kinetic data are compatible with a ternary complex sequential mechanism in which the rate of product dissociation from the reoxidized enzyme form represents the rate-limiting step. Although glycine oxidase and D-amino acid oxidase differ in substrate specificity and amino acid sequence, the kinetic mechanism of glycine oxidase is similar to that determined for mammalian D-amino acid oxidase on neutral D-amino acids, further supporting a close similarity between these two amine oxidases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Oxidoreductases / chemistry*
  • Amino Acid Oxidoreductases / metabolism*
  • Bacillus subtilis / enzymology*
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / metabolism*
  • Catalysis
  • Glycine / chemistry
  • Glycine / metabolism
  • Kinetics
  • Oxidation-Reduction
  • Oxygen / chemistry
  • Proline / chemistry
  • Proline / metabolism
  • Sarcosine / chemistry
  • Sarcosine / metabolism
  • Spectrophotometry
  • Structure-Activity Relationship
  • Substrate Specificity

Substances

  • Bacterial Proteins
  • Proline
  • Amino Acid Oxidoreductases
  • glycine oxidase
  • Oxygen
  • Glycine
  • Sarcosine