Abnormally High Content of Free Glucosamine ResiduesIdentified in a Preparation of Commercially Available Porcine IntestinalHeparan Sulfate

摘要

Heparan sulfate (HS) polysaccharides are ubiquitous in animal tissues as components of proteoglycans, and they participate in many important biological processes. HS carbohydrate chains are complex and can contain rare structural components such as N-unsubstituted glucosamine (GlcN). Commercially available HS preparations have been invaluable in many types of research activities. In the course of preparing microarrays to include probes derived from HS oligosaccharides, we found an unusually high content of GlcN residue in a recently purchased batch of porcine intestinal mucosal HS. Composition and sequence analysis by mass spectrometry of the oligosaccharides obtained after heparin lyase III digestion of the polysaccharide indicated two and three GlcN in the tetrasaccharide and hexasaccharide fractions, respectively. ¹H NMR of the intact polysaccharide showed that this unusual batch differed strikingly from other HS preparations obtained from bovine kidney and porcine intestine. The very high content of GlcN (30%) and low content of GlcNAc (4.2%) determined by disaccharide composition analysis indicated that N-deacetylationand/or N-desulfation may have taken place. HS iswidely used by the scientific community to investigate HS structuresand activities. Great care has to be taken in drawing conclusionsfrom investigations of structural features of HS and specificitiesof HS interaction with proteins when commercial HS is used withoutfurther analysis. Pending the availability of a validated commercialHS reference preparation, our data may be useful to members of thescientific community who have used the present preparation in theirstudies.