A monitoring system for energy transduction by bacteriorhodopsin liposomes

A computer-controlled system and custom software are described that collect information and perform computations to quantify important parameters of energy transduction during the conversion of photons into a proton electrochemical gradient (Delta<(mu)over tilde>(H+)) by bacteriorhodopsin (BR)-liposomes. The strong actinic light used to energize the BR-liposomes causes several serious problems for the approaches commonly used to measure these parameters. This paper identifies these problems and presents solutions that permit the acquisition of the desired information, namely, the initial (1st sec) rate and total extent of H+ translocation, rate of H+ leakage (driven by an existing Delta<(mu)over tilde>(H+)), external, internal and delta pH values, and Delta Psi values. The system is presented with representative experimental data.