Omylosyltransferases

Omylosyltransferases is a term that is not widely used in current enzymology literature and may reflect a typographical variant of amylosyltransferases or a broader class of glycosyltransferases that handle amylosyl (glucan) units. In this alternative framing, omylosyltransferases would denote enzymes that catalyze the transfer of glucan residues, typically from activated donors such as UDP-glucose or ADP-glucose, to growing glucan acceptors and thereby elongate starch- or glycogen-like chains.

Functionally, amylosyl- or omylosyltransferase–type activities are involved in the biosynthesis of glucan polymers such as amylose and amylopectin in plants or analogous glucan structures in bacteria. The reactions form glycosidic bonds, often alpha-1,4 or alpha-1,6 linkages, and operate within the larger glycosyltransferase superfamily. Donor specificity, acceptor type, and linkage formation can vary among enzymes described under this umbrella, and the mechanism may be retaining or inverting depending on the family.

In plants, starch biosynthesis relies on a set of glucan-elongating enzymes, including granule-bound and soluble starch synthases, which are related to the general concept of amylosyltransferases through their role in transferring glucosyl residues to a growing polymer. In bacteria, similar activities contribute to glycogen- or starch-like glucan assembly. Because nomenclature is inconsistent, precise annotation should be verified against primary sources or database entries to determine whether a given omylosyltransferase entry corresponds to an amylosyltransferase or a broader glycosyltransferase category.

See also: glycosyltransferase, amylosyltransferase, starch biosynthesis, glucan polymer.