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PubMed1965

THE CELL-BOUND ALPHA-AMYLASES OF STREPTOCOCCUS BOVIS.

1. The cell-bound alpha-amylase of Streptococcus bovis has been isolated from other carbohydrases in the cell extract by chromatography on DEAE-cellulose. The enzyme has been compared with the extracellular alpha-amylase produced by this organism. 2. The two amylases had similar action patterns on amylose, the main product being maltotriose with smaller amounts of maltose and a little glucose. 3. The cell-bound amylase hydrolysed maltopentaose and maltohexaose at a similar rate to the hydrolysis of amylose. Maltotetraose was hydrolysed six times more slowly, and maltotriose 280 times more slowly, than amylose. 4. Studies with end-labelled maltodextrins revealed that the cell-bound alpha-amylase preferentially hydrolysed the third linkage from the non-reducing end, liberating maltotriose. The linkage at the reducing end of maltotriose was more easily hydrolysed than the other. 5. Egg-white lysozyme and the extracellular enzymes of Streptomyces albus lysed the cell walls of Streptococcus bovis, releasing amylase into the medium. In the presence of 0.6 m-sucrose 10% of the maximal amylase activity was released by lysozyme. Suspension of the spheroplasts in dilute buffer caused the rupture of the cytoplasmic membrane and the liberation of amylase. 6. A sensitive method for determining the ability of amylases to degrade starch granules is described.

Amylases↗
PubMed1964

STUDIES RELATING TO THE SERUM RESISTANCE OF CERTAIN GRAM-NEGATIVE BACTERIA.

Paracolobactrum ballerup, an organism considered completely insusceptible to the bactericidal action of the antibody-complement system, became extremely sensitive to immune serum and even to normal serum, in conjunction with complement, when cultivated at temperatures above 37 degrees C. This conversion to serum sensitivity was associated with the loss of the organism's Vi antigen and its tendency to assume a rough state. It did not result in a genetic change in the organism, however, since reincubation of serum-sensitive P. ballerup at 37 degrees C resulted in a restoration of its resistance. The loss of serum resistance as a result of cultivation temperatures above 37 degrees C may be of significance as an example of the enhancement of host defense mechanisms induced by fever. Special conditions of testing indicated that P. ballerup cultured at 37 degrees C and S. paratyphosa C, organisms considered insusceptible to serum bactericidal action, were not entirely refractory to serum. These conditions included simply a relatively low ratio of the number of test organisms to serum volume and an extended incubation period of the organisms with serum bactericidal substances, or even without these substances, prior to the initiation of bactericidal action. It is likely, therefore, that an absolute distinction between serum-sensitive and serum-resistant Gram-negative organisms does not exist, but rather that there is a very broad distribution of serum sensitivity among these organisms.

Animals↗
PubMed1965

THE LYSIS OF CELL WALLS OF GROUP A STREPTOCOCCI BY STREPTOMYCES ALBUS ENZYME TREATED WITH DIISOPROPYL FLUOROPHOSPHATE. CHARACTERISTICS OF THE LYTIC REACTION AND THE SOLUBLE CELL WALL FRAGMENTS.

Diisopropyl fluorophosphate (DFP) effectively inhibited proteolytic activity in preparations of partially purified Streptomyces albus enzyme used to lyse cell walls of Group A streptococci. Lysis of non-trypsinized Group A cell walls with DFP-treated S. albus enzyme released a soluble protein fraction containing antigenic type-specific M protein, a carbohydrate fraction consisting of Group A and a small amount of A-variant polysaccharides, and a dialyzable fraction. The similarities of the products of DFP-treated S. albus enzyme lysis of streptococcal cell walls to those released by phage muralytic enzyme furnish additional evidence of the close relationship of these wall lysins. In view of small differences in electrophoretic mobility, immunodiffusion, and chemical composition, it is suggested that Group A streptococcal cell wall polysaccharide dissolved by DFP-S. albus enzyme consists of a spectrum of molecules having the same immunological determinants but differing in content of conjugated mucopeptide.

Bacteriolysis↗