title: Effect of anaerobiosis and glucose on the content of haem and its precursors in intact yeast cells.
abstract: The content of haem and its precursors was determined in yeast cells grown under various conditions. The cells grown aerobically on 2% galactose contain about three times more haem (about 300 nmoles/g dry wt.) than the cells grown on 10% glucose. A trace amount of haem was found in anoxia irrespective of the carbon source used. The "efficiency" of the first enzyme of the haem biosynthetic pathway--delta-aminolevulinic acid (ALA) synthetase--expressed as the sum of all intermediates of the pathway in the cells grown on galactose, is similar in anaerobic and aerobic cells. The "efficiency" of the second enzyme--ALA dehydratase--is lower about three times both in anoxia and under conditions of glucose repression. In anoxia, not haem but delta-aminolevulinic acid is the main biosynthetic product. The role of glucose repression and of the feedback mechanisms in regulation of haem synthesis in yeast is discussed. A method for haem determination in the intact yeast cells, based on the formation of pyridine haemochrome, is described.
mesh_terms: D000624:5-Aminolevulinate Synthetase / Q000378:metabolism; D000622:Aminolevulinic Acid; D000693:Anaerobiosis; D003470:Culture Media; D005947:Glucose / Q000494:pharmacology; D006418:Heme / Q000096:biosynthesis*; D000623:Porphobilinogen Synthase / Q000378:metabolism; D015003:Yeasts / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*
chemical_list: D003470:Culture Media; D006418:Heme; D000622:Aminolevulinic Acid; D000624:5-Aminolevulinate Synthetase; D000623:Porphobilinogen Synthase; D005947:Glucose