THE PROTEINS IN UNHEATED CULTURE FILTRATES OF HUMAN TUBERCLE BACILLI

Abstract

Concd. culture filtrates of 2 strains of human tubercle bacilli, a virulent and a slightly virulent one, were fractionated to give 14 fractions in each case. Chemical detns. and sedimentation velocity measurements were carried out on those fractions for which significant results could be obtained. The evidence was that 2 distinct proteins were present, in addition to a polysaccharide and nucleic acid. The physical measurements did not demonstrate the presence of any other proteins. One of the proteins was isolated in pure form, and found to have a mol. wt. of 44,000 [plus or minus] 5,000, based on the partial specific volume, 0.738, sedimentation velocity, 3.4S and diffusion rate, 7.3 X 10-7cm.2/sec). This protein is believed to be the same as one previously isolated by Seibert et al., who assigned it a wt. of 32,000. The other protein was not obtained sufficiently free from polysaccharide so that its mol. wt. could be detd., but the evidence was that it had the same sedimentation constant as the polysaccharide, about 2S. Sedimentation and diffusion constants were obtained for the polysaccharide, which appeared to be a homogeneous molecular species with a wt. of about 20,000.