Lysis of nitrofurantoin-resistant strain of Vibrio el tor.

Abstract: Since 1922 when Wu proposed the use of the Folin phenol reagent for the measurement of proteins, a number of modified analytical procedures utilizing this reagent have been reported for the determination of proteins in serum, in antigen-antibody precipitates, and in insulin. Although the reagent would seem to be recommended by its great sensitivity and the simplicity of procedure possible with its use, it has not found great favor for general biochemical purposes. In the belief that this reagent, nevertheless, has considerable merit for certain application, but that its peculiarities and limitations need to be understood for its fullest exploitation, it has been studied with regard to effects of variations in pH, time of reaction, and concentration of reactants, permissible levels of reagents commonly used in handling proteins, and interfering substances. Procedures are described for measuring protein in solution or after precipitation with acids or other agents, and for the determination of as little as 0.2 gamma of protein.

Abstract: Simple sugars, oligosaccharides, polysaccharides, and their derivatives, including the methyl ethers with free or potentially free reducing groups, give an orangeyellow color w-hen treated with phenol and concentrated sulfuric acid. The reaction is sensitive and the color is stable. By use of this phenol-sulfuric acid reaction, a method has been developed to determine submicro amounts of sugars and related substances. In conjunction with paper partition chromatography the method is useful for the determination of the composition of polysaccharides and their methyl derivatives.

Abstract: Summary The technique of disc electrophoresis has been presented, including a discussion of the technical variables with special reference to the separation of protein fractions of normal human serum.

Abstract: When Escherichia coli cells are converted into spheroplasts by means of ethylenediaminetetraacetate and lysozyme (1)) most of the inducible alkaline phosphatase (2, 3) is released into the surrounding sucrose-tris(hydroxymethyl)aminomethane-HCl medium (4, 5), and a large fraction of the “latent” ribonuclease (6-8) and the ribonucleic acid inhibited deoxyribonuclease (9) is also set free (lO).r We have since found that three additional enzymes are liberated: a Co tf-stimulated 5’-nucleotidase, not previously described in E. co& an acid phosphatase; and a cyclic phosphodiesterase (11, 12). A total of 10 other enzymes have been examined and found to remain entirely within the spheroplasts. Various lines of evidence suggest that the enzymes which are released occur at or near the cell surface. We have also developed a new method for releasing most of these enzymes in high yield without greatly impairing the viability of the cells. The procedure involves osmotic shock. E. coli are first suspended in a concentrated solution of sucrose, which does not penetrate the cells, and ethylenediaminetetraacetate is added. Then they are suddenly shifted to a medium of low osmotic strength. This causes the release of the phosphatases and of the cyclic phosphodiesterase in a yield of 70% or more. A preliminary report of this work has appeared (13).