Tyrosinase activity in human skin. Influence of race and age in newborns

Abstract

Tyrosinase was measured in homogenates of foreskins from newborn babies. The tyrosine hydroxylation reaction is dependent upon 3,4 dihydroxyphenylalanine as a cosubstrate, and the Km for tyrosine is 0.15 mM, similar to the value observed for other mammalian tyrosinases. The mean enzyme activity for black babies (n = 169) is about 2.25 times that for white babies (n = 82). For white babies there is a significant correlation between age at circumcision and tyrosine activity. For black babies this correlation becomes significant when 4 individuals with extremely high tyrosine activities are omitted from the series.