Abstract
Summary
A procedure for obtaining a 50-fold purification of mammalian tyrosinase on hydroxyapatite has been described. Various highly purified samples of tyrosinase have been studied in the ultracentrifuge. The preparations were not homogeneous. The per cent of copper present in highly purified fractions was shown to be 0.22 to 0.25%. although it cannot be concluded this is an integral part of the enzyme, since prolonged dialysis inactivates the enzyme and the addition of copper did not restore the activity. Qualitative analysis for amino acids by paper chromatography indicated leucine and/or isoleucine, valine, alanine, proline, glutamic and aspartic acid, lysine, glycine, threonine, serine, and cysteic acid (probably from cystine) were present in significant amounts. Traces of phenylalanine, tyrosine, methionine, arginine, and histidine were also present.
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