Studies in immunochemistry. 18. The isolation and properties of a sialomucopolysaccharide possessing blood-group Lea specificity and virus-receptor activity

Abstract

A sialomucopolysaccharide isolated from ovarian-cyst fluid obtained from a person of blood phenotype A Le(a+) is closely similar in chemical composition and physical properties to the blood-group-specific mucopolysaccharides obtained earlier from pseudo-mucinous ovarian-cyst fluids. The material contains 18% of sialic acid in addition to the fucose, galactose, glucosamine, galactosamine and amino acids usually found. The sialic acid, which is most probably present as N-acetylneuraminic acid, is readily removed by acid at pH 1.9 and 37[degree] or by receptor-destroying enzyme. The sialomucopolysaccharide is an active Lea-specific substance and a potent inhibitor of the hemagglutination by heated type A and B influenza viruses. The removal of the sialic acid component by receptor-destroying enzyme leaves a mucopolysaccharide which has no capacity to inhibit viral hemagglutination, but is fully active as a Lea substance. The destruction of the Lea specificity by a Lea-destroying enzyme obtained from Trichomonas foetus leaves a mucopolysaccharide which contains sialic acid and is an inhibitor of viral hemagglutination. The sialomucopolysaccharide precipitates with anti-pneumococci Type XIV horse serum. The degree of precipitation is considerably enhanced after the removal of the sialic acid by receptor-destroying enzyme. The sialomucopolysaccharide is an example of a naturally occurring macromolecule which possesses 2 biological activities, each of which is associated with a different chemical structure.