Charge interactions of cytochrome c with cytochrome c oxidase.
The pyridoxal phosphate (PLP) modification of the lysine amino groups in cytochrome c causes decrease in the reaction rate with cytochrome c oxidase. The rate constants for (PLP)2-cyt. c, PLP(Lys 86)-cyt. c, PLP(Lys 79)-cyt. c and native cytochrome c (at pH 7.4, I = 0.02) are 3.6 X 10(-3) sec-1, 5.5 X 10(-3) sec-1, 5.2 X 10(-3) sec-1 and 9.8 X 10(-3) sec-1, respectively. In spite of the same positive charge of singly PLP-cytochromes c the reaction between PLP(Lys 86)-cyt. c and cyt. c oxidase exhibits the ionic strength dependence that differs from those of the PLP(Lys 79)-cyt. c. The rate constants at zero and infinite ionic strength for PLP(Lys 86)-cyt. c is 2-fold less than that for PLP(Lys 79)-cyt. c. The positively charged cytochrome c lysines 86 and 79 form two from four or five predicted complementary charge interactions with carboxyl groups on cytochrome c oxidase.
D000818:Animals; D001665:Binding Sites; D003574:Cytochrome c Group; D004563:Electrochemistry; D003576:Electron Transport Complex IV / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D009994:Osmolar Concentration; D011732:Pyridoxal Phosphate
D003574:Cytochrome c Group; D011732:Pyridoxal Phosphate; D003576:Electron Transport Complex IV