Abstract
A method consisting of gradient polyacrylamide gel electrophoresis, visualization of the enzyme with a staining technique based on substrate conversion, and densitometric scanning of the stained gel has been developed for quantitative measurement of rat plasma ES-1 activity. ES-1 activities were expressed as total peak areas. Reproducibility of the method was found to be about 10% (expressed as apparent between-gel coefficient of variation). When the ES-1 zone areas was expressed relative to that of a plasma ES-1 standard, reproducibility was about 3%. The kinetics of catalysis of alpha -naphthyl acetate hydrolysis by ES-1 could be determined with the gel scanning assay; the K sub(m) was 0.76 mM.