title: Oscillations of enzyme activities during the cell-cycle of a glucose-repressed fission-yeast Schizosaccharomyces pombe 972h-.
abstract: 1. Increased specific activities of cytochrome c oxidase, catalase, succinate dehydrogenase, succinate-cytochrome c oxidoreductase, NADH-cytochrome c oxidoreductase and malate dehydrogenase were observed during glucose de-repression of Schizosaccharomyces pombe. 2. The cell-cycle of this organism was analysed by three different methods: (a) harvesting of cells at intervals from a synchronous culture, (b) separation of cells by rate-zonal centrifugation into different size classes and (c) separation of cells by isopycnic-zonal centrifugation into different density classes. 3. Measurement of enzyme activities during the cell-cycle showed that all the enzymes assayed [cytochrome c oxidase, catalase, acid p-nitrophenylphosphatase, NADH-dehydrogenase, NADH-cytochrome c oxidoreductase, NADPH-cytochrome c oxidoreductase, succinate dehydrogenase, malate dehydrogenase, isocitrate dehydrogenase (NADP) and fumarate hydratase] show periodic expression as ;peaks'. 4. Cytochrome c oxidase shows a single maximum at 0.67 of a cycle, whereas succinate dehydrogenase exhibits two maxima separated by 0.5 of a cell-cycle. 5. All other enzymes assayed showed two distinct maxima per cell-cycle; for catalase, malate dehydrogenase and NADPH-cytochrome c oxidoreductase there is the possibility of multiple fluctuations. 6. The single maximum of cytochrome c oxidase appears at a similar time in the cycle to one maximum of each of the other enzymes studied, except for NADH dehydrogenase. 7. These results are discussed with reference to previous observations on the expression of enzyme activities during the cell-cycle of yeasts.
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D001203:Ascomycota / Q000201:enzymology*; D002374:Catalase / Q000378:metabolism; D002455:Cell Division; D002469:Cell Separation; D002499:Centrifugation, Density Gradient; D002501:Centrifugation, Zonal; D003579:Cytochrome Reductases / Q000378:metabolism; D003574:Cytochrome c Group; D003576:Electron Transport Complex IV / Q000378:metabolism; D005649:Fumarate Hydratase / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology; D007521:Isocitrate Dehydrogenase / Q000378:metabolism; D008291:Malate Dehydrogenase / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D009596:Nitrophenols; D010088:Oxidoreductases / Q000378:metabolism*; D013385:Succinate Dehydrogenase / Q000378:metabolism; D013386:Succinates
chemical_list: D003574:Cytochrome c Group; D009596:Nitrophenols; D013386:Succinates; D010088:Oxidoreductases; D008291:Malate Dehydrogenase; D007521:Isocitrate Dehydrogenase; D002374:Catalase; D013385:Succinate Dehydrogenase; D009247:NADH, NADPH Oxidoreductases; D003579:Cytochrome Reductases; D003576:Electron Transport Complex IV; D000135:Acid Phosphatase; D005649:Fumarate Hydratase; D005947:Glucose