Co-operative functioning of the dimeric haemoglobin obtained from the radular muscle of the amphineurian mollusc Amaurochiton glaucus

Abstract

1. 1. The isolated dimeric haemoglobin of the chiton Amaurochiton glaucus binds carbon monoxide in a co-operative process ( n = 1.4). 2. 2. A two-state analysis of carbon monoxide binding yields equilibrium values for the three co-operative parameters L, K R and K T. 3. 3. Subsequent to complete flash photolysis recombination with carbon monoxide exhibits accelerating time courses. Partial photolysis yields exponential time courses from which the rate of combination of the R state ( K R) can be determined. 4. 4. Computer modeling of the accelerating time courses allows an estimation of K T, the rate of combination of the T state. 5. 5. The combination of derived equilibrium and kinetic parameters allows a complete kinetic description of the co-operative function of the dimer. The validity of the parameters has been tested by simulation and comparison of the predicted and experimentally determined kinetic time courses of carbon monoxide binding.