O-sulfate esters of hydroxy amino acids in hydrolyzates of proteoglycans

✍ Scribed by Dominic D. Dziewiatkowski; Rick L. Riolo; Vincent C. Hascall

• Publisher: Elsevier Science
• Year: 1972
• Tongue: English
• Weight: 617 KB
• Volume: 50
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(72)90053-x

✦ Synopsis

Proteoglycans, macromolecules isolated from connective tissues, contain large proportions of sulfated glycosaminoglyoans covalently attached to protein (1). Amino acid (AA) analyses of acid 'hydrdlydates of proteoglycans by the methods of Spackman, Skein, and Moore (2) contain variable amounts of unidentified ninhydrin-reactive materials which elute before aspartic acid. Some of these materials appear near the' position of cysteic acid in the analyses even when precautions are tal+ to prevent its formation (3). It seemed possible that these peaks ,yepresent products of reactions between hydroxy amino acids and/or hexosamines with sulfate residues released during acid hydrolysis of the proteoglycans. This suggestion is reinforced by the report of Murray and Milstein (4), who observed the formation of the O-sulfates of serine and threonine when proteins were hydrolyzed in the presence of small amounts of sulfate. Further examination of the literature revealed that, ea+lier, Moore (5) had cautioned against preparing hydrolyzates in the presence of appreciable quantities of sulfate or phosphate because he found that significant amounts of serine were converted to serine O-sulfate in a model system containing inorganic sulfate. Indeed, more than 25 years ago, Reitz et al. ( 6) noted that mild treatment of proteins with sulfuric acid led to the formation of sulfate esters of the hydroxy amino acids.

This paper describes the results of experiments which attempt to identify these ninhydrin-positive materials. O-Sulfate esters of hydroxyamino acids were synthesized and a chromatographic system was developed for separating and quantitating them.