Hyaluronan synthases (HASs) are glycosyltransferases that catalyze polymerization of
hyaluronan found in vertebrates and certain microbes. HASs transfer two distinct
monosaccharides in different linkages and, in certain cases, participate in polymer transfer
out of the cell. In contrast, the vast majority of glycosyltransferases form only one sugar
linkage. Although our understanding of HAS biochemistry is still incomplete, very good
progress has been made since the first genetic identification of a HAS in 1993. New …