A preliminary genetic interpretation of the esterase isozymes of human tissues.

1. The esterase isozymes of human tissues have been investigated using the technique of starch-gel electrophoresis. Conventional naphthyl-azo dye linked stains and new fluorogenic staining methods were used to detect the isozymes. 2. Multiple isozymes were identified in every tissue and they were characterized in terms of their electrophoretic mobility, tissue distribution, developmental changes in utero, substrate specificity, inhibition properties and molecular weight. On these criteria 13 sets of esterase isozymes were identified, in addition to the esterase isozymes due to cholinesterase and carbonic anhydrase. 3. The data suggest that the 13 sets of isozymes are determined by at least nine different structural gene loci. 4. No electrophoretic variants were identified in a limited population survey of post-mortem tissues from adults and foetuses, except for the previously described esterase D (ESD) phenotypes.