| abstract |
An isolated protein substantially free of contamination with cytochrome b 5 and cytochrome b 5 reductase, whichn a) is a product of a prokaryotic or eukaryotic expression of an exogenous DNA, b) catalyzes the conversion of CMP-Neu5A to CMP-Neu5Gc, and c) is coded by the DNA sequence shown in SEQ ID NO:1; d) is coded by DNA sequences, which hybridize with SEQ ID NO:1 under stringent conditions; or e) is coded by DNA sequences, which, if there was no degeneracy of the genetic code, would hybridize under stringent conditions with the sequences defined in c) to d), is useful for the production of CMP-N-acetylneuramic acid hydroxylase-deficient cells. Such cells are preferably used for the production of recombinant proteins lacking N-glycoloylneuraminic acid side chains. |