PURIFICATION AND PROPERTIES OF METHANOL DEHYDROGENASE AND ALDEHYDE DEHYDROGENASE FROM METHYLOBACILLUS-GLYCOGENES

Methanol dehydrogenase (MDH) and aldehyde dehydrogenase (ALDH) were purified to a homogenous state from Methylobacillus glycogenes, an obligate methylotroph. MDH (M(r) 140,000) was composed of two different subunits (M(r) 60,000 and 9,000) forming an alpha2beta2 structure. MDH was indicated as a metalloquinoprotein containing one atom of calcium (Ca) per enzyme molecule. Binding of Ca was so tight that it was hard to remove Ca completely without denaturation of enzyme protein. A partially resolved enzyme resumed its original enzyme activity upon exogenous addition of Ca. Purified ALDH (M(r) 144,000) was composed of two identical subunits of molecular mass of 72,000. ALDH was proved to be a quinoprotein in which PQQ is bound covalently.