title: Early reduction of cytochrome c in hypoxia.
abstract: Shifts of the steady state of cytochromes a, a3 and c at high pO2 values are cited as evidence of the low O2 affinity of cytochrome oxidase in vivo [(1971) Brain Res. 108, 143-154; (1985) Adv. Exp. Med. Biol. 191, 833-842; (1987) in: Int. Soc. Oxygen Transp. Tissue, Sapporo, p. 84]. Highly aerobic, small diploid yeast cells show less than 0.44% change of steady state in the interval prior to an abrupt reduction of cytochrome c. Thus, 'pre-reduction' seems falsified as a physiological response of metabolizing yeast cells that are free of hemoglobin, do not aggregate and maintain a steady state. Pre-reduction may be due to spectroscopic interference, for example hemoglobin deoxygenation, to oxygen gradients in aggregated cells and tissues or to non-steady states of substrate and metabolic controls, as contrasted to an altered cytochrome oxidase oxygen affinity in vivo.
authors.affiliation: Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia 19104.
authors.forename: B
authors.initials: B
authors.lastname: Chance
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D003574:Cytochrome c Group / Q000378:metabolism*; D007700:Kinetics; D010084:Oxidation-Reduction; D010100:Oxygen; D010313:Partial Pressure; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D013053:Spectrophotometry
chemical_list: D003574:Cytochrome c Group; D010100:Oxygen