Modification of sialyl residues of glycoconjugates by reductive amination. Characterization of the modified sialic acids.
The sialic acid residues of alpha 1-acid glycoprotein and fetuin were modified by introduction of an amino residue, such as glycine and [3H]glycine. This modification involved (a) the selective periodate oxidation of the exocyclic carbon atoms of the sialic acid residue generating an aldehyde group at C-7, and (b) the reduction of the Schiff base formed with an amino compound by use of sodium cyanoborohydride. Thin layer chromatography, high pressure liquid chromatography, and amino acid composition data of the modified glycoprotein showed that the conversion was essentially quantitative. The glycine-modified sialic acids were isolated by mild acid hydrolysis and identified by g.l.c.-m.s. and n.m.r. spectroscopy, thus confirming that the quantitative modification produced a glycine-aminated C-7 sialic acid analog. Strong acid hydrolysis of the glycine-modified sialic acid yielded a fragment that had chromatographic characteristics similar to those of glycine.
Murray
M C
MC
Department of Biological Chemistry, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.
Bhavanandan
V P
VP
Davidson
E A
EA
Reinhold
V
V
D055598:Chemical Phenomena; D002621:Chemistry; D002853:Chromatography, Liquid; D008401:Gas Chromatography-Mass Spectrometry; D005998:Glycine; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D019158:N-Acetylneuraminic Acid; D009961:Orosomucoid; D010084:Oxidation-Reduction; D012545:Schiff Bases; D012794:Sialic Acids; D013858:Thiobarbiturates; D000509:alpha-Fetoproteins
D009961:Orosomucoid; D012545:Schiff Bases; D012794:Sialic Acids; D013858:Thiobarbiturates; D000509:alpha-Fetoproteins; D019158:N-Acetylneuraminic Acid; C029684:thiobarbituric acid; D005998:Glycine