Glycobiology World Congress

Biography

Biography: John F. Robyt

Abstract

Glycan biosynthesis has recently undergone a revolutionary change as to the understanding of how both α- and ß-linked glycans are biosynthesized. Back in the 1940’s C. S. Hanes observed that potato phosphorylase transferred 2-3 glucose units from α-D-Glc-1-P to the nonreducing ends of starch chains. This observation set the stage that starch biosynthesis required a primer. In the 1960’s Luis Leloir found that starch was biosynthesized from ADPGlc. In the late 1960’s, Robbins et al. using pulse and chase techniques found that Salmonella O-antigen was biosynthesized by the transfer of a tetra-saccharide from bactoprenol pyrophosphate to the reducing-ends of a growing chain. Four years later Ward and Perkins showed that the bacterial cell wall, murein, was also biosynthesized by the addition of the NAG-NAM-pentaphosphate to the reducing-ends of growing chains. A year later Robyt, et al. using pulse and chase experiments showed that dextran was biosynthesized by the addition of glucose from sucrose to the reducing ends of a growing dextran chains. Some years later (2007) they showed a two-site insertion mechanism for dextran biosynthesis in which glucose is added to the reducing-ends of growing dextran chains. In 2012, Mukerjea & Robyt showed that the de novo biosynthesis of starch chains by potato starch-synthase adds glucose from ADPGlc to the reducing-ends of growing starch chains. Mukerjea, McIntyre, and Robyt also found that Tris-buffers were potent inhibitors of starch-synthase and has been responsible for the perpetuation of the primer myth for starch biosynthesis, as the putative primers partially reverse the Tris-buffer inhibition.