Thermodynamic and kinetic studies of the interaction between T5-phages and their receptor, isolated from Escherichia coli b, in the absence and presence of Triton X-100.

Particles with receptor activity for T5-phages were isolated from the outer membrane of Escherichia coli B. We describe the interaction of these particles with T5-phages as a two-step chemical reaction. The rate constants were estimated from the inactivation kinetics. The transition-state theory permits the calculation of the entropy, enthalpy, and Gibbs free energy of activation. In the absence of Triton X-100, the reaction can be described with one set of thermodynamic constants for the temperature range from 10 degrees to 40 degrees C. The addition of Triton, which results in the splitting of receptor particles and in the building of mixed micelles, causes a complicated dependence on temperature. In this case, a subdividing of the temperature range measured into two parts yields two sets of thermodynamic constants that permit a good description of experimental kinetics.