The kinetics of muscle haemoglobin

Abstract

The work of Hill (1933) and Theorell (1934) has shown that mammalian muscle haemoglobin has (1) a hyperbolic dissociation curve, (2) a molecular weight of 34,000, (3) no Bohr effect. In these properties therefore it approximates more closely than blood haemoglobin to an ideal “primitive” respiratory pigment and thus constitutes a more suitable compound for kinetic investigation. A comparison of the known properties of muscle and blood haemoglobins is given in Table I. The present work consists of determinations of the velocities of combination of oxygen and carbon monoxide with muscle haemoglobin and of the velocities of dissociation of the respective saturated compounds. The results show that, at the ordinary temperature, muscle haemoglobin satisfies the minimum postulates for a “primitive” respiratory pigment, namely: (a) bimolecular combination of gas with reduced pigment; (b) unimolecular dissociation of saturated pigment; (c) mutual independence of gas-binding groups; (d) small pHeffect.