Basic Peptide of the Leucocytes Anthracidal Factor

The chopped meat is extracted by a 0.25 N H1SO4 solution for 4 days at room temperature. The filtrate is adjusted to pH 3.5 and then heated to 90° C. for 5 min. After cooling, the precipitate is discarded, and to the filtrate is added 1.5 times its volume of acetone. After 4 hr., the precipitate is resuspended in 0.1 its volume of 0.85% NaCl solution and dialyzed for 40 hr. against water at pH 3.9, adjusted to 

Bloom and Blake (75) isolated an analogous basic polypeptide from hog thyroid, utilizing essentially the same technique. The substance contained 12.6% nitrogen, and 0.78% phosphorus. Its electrophoretic analysis showed that, at pH 8.1, it migrated toward the cathode as a single irregular peak. 

In the case of B. anthracis, B. megatherium, and E. coli, the action of ribonucleic acid reverses the inhibitory effect of the peptide, whereas, in the case of hemolytic streptococci, ribonucleic acid has no action. 

The inflammatory factor, which has been shown (see p. 69) to be analogous to one of the D-glutamylpolypeptides produced by B. anthracis, also reverses the action of the basic peptide on the respiration of B. anthracis (618). The D-glutamylpolypeptide isolated from B. subtilis possesses the same properties. These phenomena of inhibition of respiration and its reversal, recall the recent observations of Katchalski et al. (340), who showed that the polypeptides resulting from the polymerisation of basic -amino acids (polylysine, polyarginine, and polyornithine) inhibit the growth of St. aureus, E. coli, and B. anthracis, whereas neither polyalanine 

Further, Weissman and Graff (621) noted that calf thymus histone also inhibits the respiration of B. anthracis, and that this inhibition is reversed by deoxyribonucleic acid. The concentration of lysine per unit of anthracidal activity is the same for the basic polypeptide and for the histone of thymus. Weissman and Graff (621) hypothesized that the basic polypeptide is a constituent of histone and is liberated from the histone by the acid and heat treatment used for the extraction of the peptide. 

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