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On the conformation change attending the hydration of lyophilized cytochrome c
Author(s) -
Aviram Irit,
Schejter Abel
Publication year - 1972
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1972.360111014
Subject(s) - chemistry , activation energy , residue (chemistry) , cytochrome c , dissolution , cytochrome , reaction rate constant , kinetic energy , kinetics , crystallography , conformational change , stereochemistry , organic chemistry , enzyme , biochemistry , quantum mechanics , mitochondrion , physics
When lyophilized cytochrome c is disolved in pH 5 to 9 buffers, a spectroscopic change can be detected with a first‐order rate constant of 0.016 sec −1 at 23°, activation energy of 24.2 kcal/mole and entropy of activation of 11 e.u. The difference spectrum obtained by extrapolating the kinetic plots to zero time indicates that the form obtained by dissolving cytochrome c is in the low spin state and lacks the 695 nm band. It is proposed that the rate process observed corresponds to a conformation change in which the lysyl‐79 residue is displaced from iron coordination by the methionyl‐80 residue.