title: Freezing injury in the yeast respiratory system.
abstract: The effect of freeze-thawing on the yeast respiratory system was studied at rapid rates of cooling. Freezing of whole cells with liquid nitrogen induced decrease of respiratory activity to under 20% of that of original cells. Mitochondria harvested from freeze-thawed cells have markedly decreased succinate oxidizing activity. Activity of succinate cytochrome c reductase was reduced significantly after freeze-thawing of whole cells while activities of succinate dehydrogenase and cytochrome c oxidase were reduced slightly. By spectrophotometric analysis it was found that about one-half the amount of cytochrome c + c1 was eluted from mitochondria to cytosol after freeze-thawing of cells. The activities of succinate oxidation in mitochondria from freeze-thawed cells were restored to normal levels by the addition of cytochrome c. Freeze-thawing of isolated mitochondria did not induce deactivation of succinate oxidizing activities and succinate cytochrome c reductase, and no elution of cytochrome c was observed. It was concluded that the decreased respiratory activities of yeast cells by freezing of cells with liquid nitrogen can be attributed primarily to the elution of cytochrome c from mitochondria.
mesh_terms: D002458:Cell Fractionation; D003576:Electron Transport Complex IV / Q000378:metabolism; D005615:Freezing; D008928:Mitochondria / Q000378:metabolism* / Q000648:ultrastructure; D010101:Oxygen Consumption; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D013384:Succinate Cytochrome c Oxidoreductase / Q000378:metabolism; D013385:Succinate Dehydrogenase / Q000378:metabolism
chemical_list: D013384:Succinate Cytochrome c Oxidoreductase; D013385:Succinate Dehydrogenase; D003576:Electron Transport Complex IV