A simple system for the measurement of the distribution of activities of individual molecules of E. coli β-galactosidase

Abstract

A simple system capable of measuring the distribution of single molecule activities of a population of E. coli β-galactosidase was developed. This system utilized a modified disposable syringe, a narrow bore capillary tube and an in-laboratory constructed laser-induced fluorescence detection system. Once started, the experiment can continue to collect data without any operator input for more than 24 h. The relative catalytic rates of 138 individual molecules of the enzyme were determined. The distribution of activities was found to be indistinguishable from that reported using more complicated methodologies.