SIMPLE-MODELS FOR THE ANALYSIS OF BINDING PROTEIN-DEPENDENT TRANSPORT-SYSTEMS

Mathematical modeling was used to evaluate experimental data for bacte rial binding protein-dependent transport systems. Two simple models we re considered in which ligand-free periplasmic binding protein interac ts with the membrane-bound components of transport. In one, this inter action was viewed as a competition with the ligand-bound binding prote in, whereas in the other, it was considered to be a consequence of the complexes formed during the transport process itself. Two sets of kin etic parameters were derived for each model that fit the available exp erimental results for the maltose system. By contrast, a model that om itted the interaction of ligand-free binding protein did not fit the e xperimental data. Some applications of the successful models for the i nterpretation of existing mutant data are illustrated, as well as the possibilities of using mutant data to test the original models and set s of kinetic parameters. Practical suggestions are given for further e xperimental design.