SCALED-UP EXPRESSION OF HUMAN ALPHA-2,6(N)SIALYLTRANSFERASE IN SACCHAROMYCES-CEREVISIAE

Expression of recombinant full length human alpha 2,6(N)sialyltransfer ase has been scaled-up in S. cerevisiae in a 150-1 bioreactor yielding 47 U at a concentration of 0.31 U/l. The protein specific activity as measured in reconstituted yeast lyophilisate was 0.8 mU/mg protein. T he recombinant enzyme exhibited similar Michaelis constants as previou sly determined for the native rat enzyme. By immunoblotting the enzyme was shown to be heterogeneous by size (44-48 kD) and N-glycosylated. We conclude that recombinant alpha 2,6(N)sialyltransferase expressed i n S. cerevisiae is retained in the endoplasmic reticulum as a fully ac tive enzyme. (C) 1995 Academic Press, Inc.