Formation of electrostatically-stabilized complex at low ionic strength inhibits interprotein electron transfer between yeast cytochrome c and cytochrome c peroxidase.
Electron transfer from yeast ferrous cytochrome c to H2O2-oxidized yeast cytochrome c peroxidase has been studied using flash photoreduction methods. At low ionic strength (mu less than 10 mM), where a strong complex is formed between cytochrome c and peroxidase, electron transfer occurs rather slowly (k approximately 200s-1). However, at high ionic strength where the electrostatic complex is largely dissociated, the observed first-order rate constant for peroxidase reduction increases significantly reaching a concentration independent limit of k approximately 1500 s-1. Thus, at least in some cases, formation of an electrostatically-stabilized complex can actually impede electron transfer between proteins.
Hazzard
J T
JT
Department of Biochemistry, University of Arizona, Tucson 85721.
McLendon
G
G
Cusanovich
M A
MA
Tollin
G
G
D003574:Cytochrome c Group / Q000378:metabolism*; D003578:Cytochrome-c Peroxidase / Q000378:metabolism*; D004579:Electron Transport; D007700:Kinetics; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000378:metabolism*
D003574:Cytochrome c Group; D010544:Peroxidases; D003578:Cytochrome-c Peroxidase