Metabolism of hydrogen peroxide by Pichia pastoris.

Hydrogen peroxide in methylotrophic yeasts can be metabolized in at least two distinct ways.Addition of exogenous hydrogen peroxide removes the dependance of catalase on endogenouslyproduced hydrogen peroxide resulting enhanced rates of alcohol oxidation.Exogenous hydrogen peroxide is also efficiently degraded by cytochrome c peroxidase (CCP), a competitive reaction which does not result in enhanced alcohol oxidation.To overcome the influence of cytochrome c peroxidase, artificial peroxisomes were prepared by coimmobilization of alcohol oxidase and catalase.These artificial peroxisomes mimic the peroxide-induced rate enhancement observed with whole cells.Growth of methylotrophic yeasts on limiting amounts of methanol results in the formation of peroxisomes containing alcohol oxidase and catalase.Alcohol oxidase oxidizes methanol, producing formaldehyde and hy-