Sialyltransferase In Human Malignant-Melanoma

A glycosyltransferase, CMP- N -acetylneuraminic acid: glycoprotein sialyltransferase was found in human malignant melanoma. Activities were measured with desialized glycoprotein as an exogenous acceptor. The enzyme was characterized by means of its pH optimum, 5.5, temperature optimum, 30° C, K M values, 10 μM for the sugar nucleotide and 0.3 mM for desialized glycoprotein. It did not require exogenously added metal ions but was slightly stimulated by Mg 2+ . It required detergent for optimal activity. The effect of nucleotides and sugar nucleotides on enzyme activity has been investigated.