The kinetic properties of glycine oxidase fromBacillus sub-tiliswere investigated using glycine, sarcosine, andD-proline as substrate. The turnover numbers at saturating substrate andoxygen concentrationswere s )1 , )1 , s )1 , respectively, with glycine, sarcosine, andD-proline as sub-strate. Glycine oxidase was converted to a two-electron reduced form upon anaerobic reduction with the individual substrates and its reductive half-reaction was demonstrated tobe reversible.