KINETIC STUDIES ON HEMOGLOBIN BY FLASH PHOTOLYSIS.
Final scientific rept., 1 Dec 65-31 Jan 67,
ROME UNIV (ITALY) ISTITUTO DI CHIMICA BIOLOGICA
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The kinetics of the reactions of human hemoglobin of isolated alpha and beta chains of hemoglobin with free and parachloromercury benzoate bound SH group and of myoglobin with O2 and CO were studied by flash photolysis, under a variety of conditions. For the isolated hemoglobin chains the velocity constants for the reaction with CO obtained by flash are higher up to 30 70 than those obtained in rapid mixing experiments. Values for the velocity constant for combination of isolated hemoglobin chains with O2 were measured. These values are higher than those predicted from values of equilibrium constant and dissociation velocity constants. The origin of rapidly reacting forms of hemoglobin on flash photolysis was investigated. The rapidly reacting form appearing at pH 7 in dilute hemoglobin solutions was correlated to differential aggregation of ligand bound and deoxy hemoglobin. A study of the quantum yield for photodissociation of CO heme proteins was carried out. The relation, supposed in the past, between quantum yield and state of polymerization of the heme proteins, was disproved, the quantum yield appearing to depend primarily on the primary structure of the protein. Author