The Biochemistry of Cytochrome C in Relation to Maternally Inherited Phenotypes of Neurospora

Citation

Hardesty, Boyd Archer (1961) The Biochemistry of Cytochrome C in Relation to Maternally Inherited Phenotypes of Neurospora. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/NQE0-YY21. https://resolver.caltech.edu/CaltechETD:etd-04032006-102552

Abstract

Cytochrome c from Neurospora was isolated and its properties studied with respect to its role as a protein accumulated in the extrachromasomal mutants, poky and mi 3. All samples of cytochrome isolated using several different procedures were electrophoretically heterogeneous. Further, electrophoretic differences were observed in the cytochrome c isolated from the different strains of Neurospora although cytochrome c from poky and wild type appeared homogenous during sedimentation and had very similar sedimentation coeffiecients. In contrast to wild type Neurospora, cytochrome c in homogenates of 2.5 day old poky was found to remain largely in the supernatant fraction after high speed centrifugation suggesting that the enzyme in poky is not bound to mitochondria or any other particulate, subcellular structure. Lipid extracts from poky were found to contain up to 36 times the amount of total free fatty acids present in similar extracts from wild type although the chemically bound fatty acids of the two strains were similar. The interaction of free fatty acids with mammalian cytochrome c was studied in detail and it was suggested that they may cause an unfolding of the protein portion of the cytochrome c molecule therby exposing the heme to direct interaction with such compunds as hydrogen peroxide or molecular oxygen. Thus the large amounts of free fatty acid present in poky might allow its cytochrome c to function as the terminal oxidase in place of cytochromes a + a3 present in wild type Neurospora but not found in poky.

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