ISSN:
0006-3525
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
In order to get an idea of the transient and stationary behavior to be looked for in a biological macromolecular system such as an enzyme or respiratory protein in the presence of its ligands, we have studied the coupled kinetic equations applicable to a simple allosteric model, based on the concerted two-state model of Monod et al. [(1965) J. Mol. Biol. 12, 88-118]. Exact solutions of the equations are given for three special cases, and two complementary methods are developed to generate approximate solutions in the general case, always, however, with the assumption that the equations are linear due to maintenance of ligand activity at a constant level. Subject to this assumption, these approximation methods have applicability to coupled rate equations beyond those considered here. As an illustration of how the results can provide the basis for a detailed analysis of actual kinetic data on working proteins, the formalism is applied to the kinetics of binding of oxygen by hemoglobin. An important result is that although time evolution to the steady state is in principle determined by several relaxation times, the effect of cooperativity for the case considered is to establish the dominance of one of them relative to the others. This suggests that for a macromolecule with a large number of binding sites, only one, or at most a few, of the many possible relaxation times are significant for specification of cooperative kinetics. The methods developed here, which will be applied more extensively elsewhere, provide a systematics for finding these dominant relaxation times.
Zusätzliches Material:
3 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/bip.1980.360190411
Permalink
