Formation and Distribution of Modified FAD between Isozymes of Alcohol Oxidase in the Methylotrophic Yeast Pichia methanolica

V. V. Ashin and Y. A. Trotsenko^*

Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow Region, 142292 Russia; fax: (095) 923-3602; E-mail: trotsenko@ibpm.serpukhov.su

^* To whom correspondence should be addressed.

Received February 13, 1998; Revision received April 22, 1998

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The content of modified FAD (mFAD) in isoforms of alcohol oxidase (AO) in the methylotrophic yeast Pichia methanolica MH4 is increased in the stationary growth phase of the culture or under lower dilution rates. The isoform with slower electrophoretic mobility has the higher mFAD content. The results of in vitro experiments and the occurrence of mFAD in AO-lacking mutants of Hansenula polymorpha DL-1 imply a biosynthetic origin of this cofactor. HPLC analysis of tryptic hydrolysates of the first and the ninth isoforms of AO from P. methanolica MH4 revealed two different types of subunits. Possible mechanism of mFAD formation and distribution between the AO isozymes is discussed.

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KEY WORDS: alcohol oxidase, isozymes, modified FAD, methylotrophic yeasts, Pichia methanolica, Hansenula polymorpha

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