A cytosolic cytochrome b5-like protein in yeast cell accelerating the electron transfer from NADPH to cytochrome c catalyzed by Old Yellow Enzyme.
A 410-nm absorbing species which enhanced the reduction rate of cytochrome c by Old Yellow Enzyme (OYE) with NADPH was found in Saccharomyces cerevisiae. It was solubilized together with OYE by the treatment of yeast cells with 10% ethyl acetate. The purified species showed visible absorption spectra in both oxidized and reduced forms, which were the same as those of the yeast microsomal cytochrome b5. At least 14 amino acid residues of the N-terminal region coincided with those of yeast microsomal b5, but the protein had a lower molecular weight determined to be 12,600 by SDS-PAGE and 9775 by mass spectrometry. The cytochrome b5-like protein enhanced the reduction rate of cytochrome c by OYE, and a plot of the reduction rates against its concentration showed a sigmoidal curve with an inflexion point at 6x10(-8) M of the protein.
Nakagawa
Manabu
M
Laboratory of Chemistry, Kansai Medical University, Hirakata 573-1136, Japan.
Yamano
Toshio
T
Kuroda
Kiyo
K
Nonaka
Yasuki
Y
Tojo
Hiromasa
H
Fujii
Shigeru
S
D002384:Catalysis; D015786:Cytochromes b5 / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism*; D003600:Cytosol / Q000201:enzymology*; D004579:Electron Transport; D009249:NADP / Q000378:metabolism*; D009252:NADPH Dehydrogenase / Q000502:physiology*; D010084:Oxidation-Reduction; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D029701:Saccharomyces cerevisiae Proteins; D009249:NADP; D045304:Cytochromes c; D015786:Cytochromes b5; D009252:NADPH Dehydrogenase