Enzymes for Glycoprotein Synthesis

Abstract

More than 90% of human proteins are glycosylated and since protein glycosylation is understood to play a role in folding, trafficking, stability, immunogenicity, and function there is a need to generate pure protein glycoforms. Pure single protein glycoforms are difficult to obtain because the cellular machinary produces complex mixtures for any given protein. In this article an overview is given of various approaches used to generate specific single glycoforms of proteins, studies of the role of glycosylation in protein stability and function, and the imaging and identification of new glycoproteins related to cancer.

Native chemical ligation with Nα acyl transfer auxiliaries

“…The mechanism is proposed to go via acyl transfer through a putative 14‐membered (in some cases, 15 or larger) ring transition, generally at a pH of 8.0 72, 73. Alternative solvents to aqueous‐based buffers have also been used to minimize hydrolysis 74. The mechanism is reminiscent of the large auxiliaries used by Kemp; however, in contrast to the very constrained, rigid assemblies designed by Kemp, these are flexible.…”

Advances in chemical ligation strategies for the synthesis of glycopeptides and glycoproteins

“…31 that can be used for the chemoenzymatic elaboration of glycopeptides and glycoproteins. [34][35][36][37][38][39][40][41][42] While this represents a powerful method for the synthesis of complex glycopeptides, there are several possible drawbacks. These include the potential for incomplete glycosylation, giving rise to glycoformic mixtures which may or may not be separable by chromatography.…”

Chemistry and glycobiology

“…1a), is to first create glycoproteins with monosaccharide moieties by trimming extra glycans with glycosidases from a recombinant glycoprotein mixture of glycoforms expressed from yeast, CHO cell or baculovirus. Then, the short saccharide-or monosaccharidecontaining proteins can be elongated with endoglycosidases [3][4][5] or recombinant glycosyltransferases 6,7 to rebuild a new glycan structure. While conceptually simple, this approach is difficult in practice because it requires each enzymatic step to go to completion in order to obtain single glycan forms.…”