Physicohemical investigations on two unusual sialic acid-rich mucoids from the intestinal tract of patients with fibvrocystic diseases of the pancreas

Abstract

The mucoids were originally excreted as tough rope-like plugs of gelatinous material. They were relatively uncontaminated apart from considerable amounts of admixed serum proteins, which were completely removed by washing with 0.9% sodium chloride solution. Sample 1 appeared to be essentially homogeneous, although somewhat poly-disperse, when examined in the ultracentrifuge. The mucoids showed many similarities in their physical and chemical properties, and were remarkable for their lack of solubility and retention of their original form under a wide variety of conditions. They resembled typical epithelial mucosubstances in their chemical composition fucose, sialic acid, hexosamine, galactose and amino acids were identified and determined. Sample 2 contained less total carbohydrate than sample 1 and a considerably lower proportion of fucose, the sialic acid: fucose ratios being 1 and 3 for samples 1 and 2 respectively; however, the relative proportions of the other sugars were similar in both mucoids. Neura-minidase and 0.1N- sulphuric acid at 80[degree] rapidly split off all the sialic acid in both samples. The mucoids were also potent inhibitors of hemag-glutination by heated type A and B influenza viruses. Thus the sialic acid residues occur as end groups in the polysaccharide portion of the mucosubstances. Apart from an unusually high phenylalanine content, the distribution of amino acids in the mucoids resembles that found in typical epithelial mucosubstances. Inorganic ions appear to be important in stabilizing the structure of the mucoids. The relationship between abnormalities in mucous and serous secretions which characterize fibrocystic disease is discussed briefly.