NADH as electron donor for the photosynthetic membrane of Chlamydomonas reinhardii

A chloroplast fraction from Chlamydomonas reinhardii cells can oxidize NADH in the light, unlike chloroplasts of higher plants. The Chlamydomonas preparation catalyzes electron flow from NADH to methylviologen or ferredoxin to evolve hydrogen (in the presence of a hydrogenase) or take up oxygen. The NADH photooxidation is sensitive to rotenone, dibromothymoquinone and dicyclohexylcarbodiimide. This suggests that a rotenone sensitive NADH dehydrogenase is coupled on the plastoquinone reduction site of the potosynthetic electron flow system. On sonication of the particles NADH photooxidation is lost but may be restored by a protein fraction from an acetone extract plus plastocyanin.Abbreviations DAD diaminodurene - DCCD dicyclohexylcarbodiimide - DCMU (3,3-dichlorphenyl)-N·N dimethyl urea - DBMIB dibromothymoquinone - DNP-INT dinitro-phenylether of 2-iodo-4-nitrothymol - MV methylviologen - chl chlorophyll Dedicated to Professor Dr. O. Kandler on the occasion of his 60th birthday