Differential enzyme activities in human esterase D phenotypes.

Red cell ESD activities have been determined in 78 individuals with ESD-1 phenotype, in 94 with ESD2-1 and in 28 with ESD-2 phenotype. The mean activities of these three groups were 276.7, 216.6 and 171.5 expressed as 10(-7) M methylumbelliferone produced/h/g Hb, respectively. The activities associated with a single ESD*1 gene are estimated to be 60% higher than ESD*2.