A3-sialyltransferase

Several a3-sialyltransferases have been cloned, and ST3Gal III is commercially available in recombinant form. A particularly interesting report of Gilbert et al. [55] describe a fusion protein consisting of CMP-Neu5Ac synthetase and o2,3-sialyl-transferase from Neisseria meningitidis. This polypeptide was able to catalyze the reactions shown in eqs (2) and (3). 

There are a number of families of similar sialyltransferases, all related to each other through homology of the sialylmotif which may be the CMP-sialic acid donor substrate binding site [93]. This class of enzymes is discussed further in Chapter 12. Two families of sialyltransferases are known to act on mucin O-glycans, Gal a3-sialyltransferases [94-98] and GalNAc a6-sialyltransferases [99-102]. 

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