title: Changes in enzyme activities and distributions during glucose de-repression and respiratory adaptation of anaerobically grown Saccharomyces carlsbergensis.
abstract: 1. During anaerobic glucose de-repression the respiration rate of whole cells of Saccharomyces carlsbergensis remained constant and was insensitive to antimycin A but was inhibited by 30% by KCN. Aeration of cells for 1 h led to increased respiration rate which was inhibited by 80% by antimycin A or KCN. 2. Homogenates were prepared from sphaeroplasts of anaerobically grown, glucose de-repressed cells and the distribution of marker enzymes was investigated after zonal centrifugation on sucrose gradients containing MgCl(2). These homogenates contained no detectable cytochrome c oxidase or catalase activity. The complex density distributions of NADH- and NADPH-cytochrome c oxidoreductases and adenosine triphosphatase(s) [ATPase(s)] were very different from those of anaerobically grown, glucose-repressed cells. 3. The specific activity of total ATPase was lowered and sensitivity to oligomycin decreased from 58 to 7% during de-repression. 4. Cytochrome c oxidase and catalase activities were detectable in homogenates of cells after 10min aeration. Zonal centrifugation indicated complex, broad sedimentable distributions of all enzyme activities assayed; the peaks of activity were at 1.27g/ml. 5. Centrifugation of homogenates of cells adapted for 30min and 3 h indicated a shift of density of the major sedimentable peak from 1.25g/ml (30min) to 1.235g/ml (3 h). After 30min adaptation a minor zone of oligomycin-sensitive ATPase and 15% of the total cytochrome c oxidase activities were detected at rho=1.12g/l; these particles together with those of higher density containing cytochrome c oxidase, ATPase and NADH-cytochrome c oxidoreductase activities were all sedimented at 10(5)g-min. 6. Electron microscopy indicated that the mitochondria-like structures of anaerobically grown, glucose-de-repressed cells were similar to those of repressed cells. After 10min of respiratory adaptation highly organized mitochondria were evident which resembled the condensed forms of mitochondria of aerobically grown, glucose-de-repressed cells. High-density zonal fractions of homogenates of cells after adaptation also contained numerous electron-dense vesicles 0.05-0.2mum in diameter. 7. The possibility that the ;promitochondria' of anaerobically grown cells may not be the direct structural precursors of fully functional mitochondria is discussed.
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000332:Aerobiosis; D000693:Anaerobiosis; D000968:Antimycin A / Q000494:pharmacology; D002374:Catalase / Q000378:metabolism; D002501:Centrifugation, Zonal; D003579:Cytochrome Reductases / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D008854:Microscopy, Electron; D010101:Oxygen Consumption; D012440:Saccharomyces / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet; D013997:Time Factors
chemical_list: D000968:Antimycin A; D002374:Catalase; D003579:Cytochrome Reductases; D003576:Electron Transport Complex IV; D000135:Acid Phosphatase; D000251:Adenosine Triphosphatases; D005947:Glucose