Studies on prevention of infection (II) The enzymologic traits and pro­tective ability of the fractions obtained from Sal. typhi by high speed centrifugation

By physically destroying typhoid bacilli and centrifuging at a high speed, an insoluble granular fraction (P1) and soluble fraction (S1) were obtained. Chemical and enzymologic properties of these substances as well as their influences on the protective ability against infection were studied; and the following results were attained: 1. P1 contains an extremely small amount of proteins when compared with S1. 2. The enzymologic activity of P1 is entirely different from that of S1. In P1 the respiratory enzyme system of only lactate and succinate is localized. 3. Although both P1 and S1 possess the antibody-producing ability in serum of rabbit to the same high degree, P1 imparts to mice a markedly high protective ability against infection. 4. By the heat-treatment of P1 its antigenicity is lost at the same time.