Oβ-(N-Acetyl-α-glucosamine-1-phosphoryl)serine in proteinase I from Dictyostelium discoideum

Abstract

Publisher Summary This chapter discusses the chemical characterization of the O β -(N-acetyl-α-glucosamine-l-phosphoryl)serine group and provides the first description of the 31 P and 13 C nuclear magnetic resonance (NMR) signals associated with this phosphodiester. Phosphoesters at the hemiacetal hydroxyls of sugars are all moderately stable to alkali, but are labile to mild acid hydrolysis. In contrast, phosphoesters at the β-hydroxyls of serine and threonine residues in proteins are moderately stable to acid hydrolysis, but are readily released by an alkali-catalyzed β-elimination reaction. Because of the differences in chemical properties of these two phosphoester bonds, it is possible to demonstrate that proteinase I from Dictyostelium discoideum contains O β -( N -acetyl-α-glucosamine-l-phosphoryl)serine. 13 C and 31 P NMR spectroscopy have been used to characterize poly- and oligosaccharides attached to glycoproteins and glycopeptides. The use of 13 C NMR spectroscopy has considerable potential as an analytical tool because most of the resonances of the carbon atoms in saccharides are well dispersed and occur in a portion of the spectrum. The results of 31 P and 13 C NMR spectroscopy provide corroborative evidence that essentially all the N -acetyl-α-glucosamine 1-phosphate residues in proteinase I are esterified to peptidylserines through phosphodiester bonds.