Action of the Lytic Principle of Pneumococcus on Certain Tissue Polysaccharides

Abstract

Avery and Cullen 1 obtained from both rough and smooth pneumococci a ferment capable of lysing heat-killed pneumococci. In unpublished experiments (Dubos) it was found that the same ferment preparation renders ineffective in rabbits the capsular type specific antigen of killed cells of virulent pneumococci.

A hydrolytic action of the ferment preparation of pneumococcus on two tissue polysaccharides is described here. This action seems to be identical with that of the same ferment on the pneumococci.

From bovine vitreous humor and from human umbilical cord two polysaccharides have been obtained in pure form, seemingly identical in composition, rotation, and general physical behavior. 2 They are composed of acetylglucosamine and glucuronic acid, the components having been shown to be present in equimolar ratio by isolation or quantitative analysis.

The 2 polysaccharide acids yielded reducing sugar following hydrolysis by the ferment obtained from pneumococcus autolysates. The hydrolysis is optimal between pH 5 and 6, and does not take place above pH 8 nor below pH 4.5. The action of the ferment on killed pneumococci has about the same pH optimum. The action on both the pneumococci and the 2 polysaccharide acids is abolished by heating the ferment or by treating it with iodine. The iodine inactivation is reversed by sulfite and to a lesser degree by arsenite, as measured by the polysaccharide hydrolysis.

Further evidence that the same principle is active against the 2 tissue polysaccharides and the pneumococci is found in the following inhibition reaction: 2.0 cc. of a 0.1 percent pneumococcus ferment solution in phosphate buffer at pH 6.0 were incubated for 6 hours with 10 mg. of polysaccharide (vitreous and umbilical cord). When tested against a suspension of heat-killed pneumococci at the end of the incubation period, the ferment was found to have lost at least 90% of its lytic activity. The control ferment solution also incubated at pH 6.0 for the same length of time in the absence of the polysaccharide retained all its activity.