The content and nature of the carbohydrate components of the organic matrix of embryonic bovine enamel

Abstract

1. 1. The carbohydrate content of the organic matrix of developing, embryonic bovine enamel has been investigated. The carbohydrates accounted for slightly more than 1% of the total weight of the organic matrix and of the fractions soluble at neutral pH. Hexose and hexosamine were present in approximately equal amounts. Galactose and galactosamine were the principal sugars identified, although mannose and trace amounts of glucose were consistently found. The neutral-insoluble, but acid-soluble fraction of the organic matrix contained slightly greater amounts of carbohydrates. These were identified as galactose and galactosamine in equimolar quantities. 2. 2. Acid mucopolysaccharides and glycopeptides were isolated after papain digestion of the neutral-soluble fraction. From uronic acid vaues of the fraction of the enamel matrix soluble at neutral pH, the acid mucopolysaccharide content of the organic matrix was estimated to be 0.20%. Glycopeptides containing as much as 20% carbohydrate were isolated by preparative polyacrylamide-gel electrophoresis. From the carbohydrate analyses of these glycopeptides, it was suggested that the major oligosaccharide moiety of the glycopeptides contains galactosamine, galactose, and mannose in a ratio of 4:3:1. 3. 3. Aldehydes and hydroxylamine-sensitive, ester-like bonds were not identified in any significant quantity in the organic matrix of embryonic bovine enamel.