SACCHAROMYCES-CEREVISIAE MITOCHONDRIA CAN SYNTHESIZE FMN AND FAD FROMEXTERNALLY ADDED RIBOFLAVIN AND EXPORT THEM TO THE EXTRAMITOCHONDRIALPHASE

Evidence is given that mitochondria isolated from Saccharomyces cerevi siae can take up externally added riboflavin and synthesise from it bo th flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) p robably due to the existence of the mitochondrial riboflavin kinase al ready reported and the novel mitochondria FAD synthetase. Moreover Sac charomyces cerevisiae mitochondria can export the newly synthesised fl avin derivatives to the extramitochondrial phase. This has been proven to take place with 1:1 stoichiometry with riboflavin decrease outside mitochondria, thus showing that flavin traffic occurs across the mito chondrial membranes. (C) 1998 Federation of European Biochemical Socie ties.