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Research Article Free access | 10.1172/JCI108014
Find articles by Pomerantz, S. in: JCI | PubMed | Google Scholar
Find articles by Ances, I. in: JCI | PubMed | Google Scholar
Published May 1, 1975 - More info
Tyrosinase has been 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 two and one-fourth times that for white babies (n = 82). For white babies there is a significant correlation between age at circumcision and tyrosinase activity. For black babies this correlation becomes significant when four individuals with extremely high tyrosinase activities are omitted from the series.