Exponential model for a two-ligand, regulatory enzyme. Part 3: Performance tests of INDEXP computer programs for...

The exponential model for a regulatory enzyme describes the relationship between the initial velocity of the catalysed reaction and the concentration of two ligands. A program, entitled 'INDEXP' has been devised to analyse rate data in terms of the model (Kinderlerer et al., 1981) and, in this report, its performance is examined when presented with experimental initial velocity data taken from the literature. It is shown that the two-ligand exponential model can satisfactorily rationalise experimental data with five linked constants (Ainsworth and Gregory, 1978); as a result the influence of ligand concentrations on the catalysed reactions can be described in rather simple terms.