This investigation was prompted by difficulties that were encountered during attempts to determine the hexosamines in a glycoprotein fraction from ram spermatozoa (1). This fraction had been hydrolyzed by heating it at 100ยฐC in presence of 0.05 N hydrochloric acid and Dowex 50 (2). Following the procedure of Anastassiadis and Common (3), the hydrolysis products were separated into (a) neutral sugars and uranic acids and (b) hexosamines and amino acids in 1.6 A' hydrochloric acid. In order to prepare fraction b for chromatographic analysis it was taken to dryness in a desiccator over sodium hydroxide and dissolved in a little water. Aliquots of this solution were dried in a rotary evaporator. During these two evaporations nearly 507& of the hexosamine was lost. Many investigators have concentrated glycoprotein hydrolyzates by vacuum evaporation (4-9) but in no case has any significant loss of hexosamine been reported.
In the following experiments mixtures of amino acids, hexosamine, and hydrochloric acid were prepared to simulate the hydrolysis products of polysaccharide-protein complexes. Methods of removing the acid and concentrating the solutions were examined with a view to minimizing losses of hexosamine.
MATERIALS AND METHODS