[New locus of cholinesterase (E3) expressed in human milk].

Analysis of structural variation in enzymes and other proteins of human milk revealed polymorphism of the protein exhibiting cholinesterase activity. The distribution of cholinesterase activity zones after electrophoresis of milk proteins in polyacrylamide gel differs from the pattern typical for serum cholinesterase. Samples of milk taken from 132 recently confined Russian women, which were obtained from Moscow district maternity hospital, were subjected to population analysis. Four phenotypes of the locus designated as E3, have been identified: 1-1, 2-1, 2-2 and 3-1. Preliminary visual evaluation of the electrophoretic pattern allows as to differentiate phenotypes in the following order according to enzyme activity: 2-2 > 2-1 > 3-1 > 1-1. It seems most probable that the revealed variants of cholinesterase E3 are determined by three alleles of one autosomic locus with the following frequencies: E31 = 0.8296; E32 = 0.1629 and E3*3 = 0.0075. The obtained distribution of E3 phenotypes is in good agreement with the expected one with chi 2(1) = 0.9378.