Effect of anaerobiosis and glucose on the content of haem and its precursors in intact yeast cells.
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.
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*
D003470:Culture Media; D006418:Heme; D000622:Aminolevulinic Acid; D000624:5-Aminolevulinate Synthetase; D000623:Porphobilinogen Synthase; D005947:Glucose