Abstract
Dimethylglycine oxidase was purified to homogeneity from the cell extract of Cylindro-carpon didymum M-1, aerobically grown in medium containing betaine as the carbon source. The molecular weight of the enzyme was estimated to be 170, 000 by the gel filtration method and 180, 000 by the sedimentation velocity method. The enzyme exhibited an absorption spectrum characteristic of a flavoprotein with absorption maxima at 277, 345 and 450nm. The enzyme consisted of two identical subunits with a molecular weight of 82, 000, and contained two mol of FAD per mol of enzyme. The flavin was shown to be covalently bound to the protein. The enzyme was inactivated by Ag+, Hg2+, Zn2+ and iodoacetate. The enzyme oxidized dimethylglycine but was inert toward choline, betaine, sarcosine and alkylamines. Km and Vmax values for dimethylglycine were 9.1mM and 1.22μmol/min/mg, respectively. The enzyme catalyzed the following reaction: Dimethylglycine+O2+H2O→sarcosine+form-aldehyde+H2O2.
