The Degradation of l-Arabinal to l-Erythrose¹

Abstract

In a previous paper2 it was shown that «/-xylal by means of ozone could be degraded to a tetrose, which was identified as «/-threose. Ozone apparently had a dualistic action. Firstly, it was added to the double bond, forming an unstable ozonide, which in turn was broken down under the influence of the solvent, acetic acid, to two aldehyde groups. Secondly, cleavage of the 1,5oxygen ring took place, a fact which had to be assumed since a free tetrose and not its 4-formyl derivative was found as the reaction product.In this present communication we report a further investigation of the reaction, using /arabinal, III, as a starting material. It could be

Acid Production and Tooth Decalcification By Oral Bacteria'

“…Measurements of acid were made by titrating with N/10 NaOH using phenolphthalein as an indicator. The pH was determined by the use of nitrazine paper followed by spot tests (8,9) with indicator solutions when the pH was below 5.2. Aliquots removed before titration were used for making counts.…”

The Purification of the Antibodies in Type I Anti-Pneumococcus Serum, and the Chemical Nature of the Type-Specific Precipitin Reaction

“…It has been shown by him that when pneumococcus antiserum is diluted with distilled water, the major portion of the antibodies separates as an insoluble precipitate. Not only can the immune bodies be precipitated by this means, but they can be effectively separated from the serum by dilution with small quantities of ethyl alcohol (5). The conditions under which antibodies can best be separated from antiserum have been thoroughly investigated (6) and the product which has been isolated has been found to have properties which definitely characterize it as a globulin more basic than ordinary serum globulin (7).…”

“…The further purification of the water-insoluble globulin bearing the immune bodies of pneumococcus antiserum has also been attempted by Felton (8). It has been shown that fractions of the protein, varying in their solubility in different 179 concentrations of sodium or ammonium sulfate, likewise vary in their capacity to protect mice against infection with standard doses of homologous virulent organisms.…”

“…The fact that the globulins of horse serum are so readily dissociable has been made use of in the present attempt to separate the immune globulin of Type I pneumococcus antiserum from accompanying inert globulins by fractionation with ammonium sulfate. The insoluble globulin fraction obtained by the dilution of antipneumococcus horse serum with distilled water, followed by the precipitation of small amounts of inert protein at pH 4.8 (8), has served as source material. By repeated fractional precipitation and dialysis this protein mixture has been separated into relatively inert euglobulin fractions, and 181 active pseudoglobulin fractions containing the major portion of the antibodies present in the starting material.…”

“…A second method has also been devised for the separation of inert protein from the active immune globulin. It has been found that when pneumococcus antibody solutions, prepared according to the method of Felton (8), are treated with 0.2 M potassium acid phthalate buffer at the appropriate hydrogen ion concentration, a precipitate of inert protein is formed, leaving in solution the immunologically active globulin. The latter can be further fractionated by ammonium sulfate and dialysis to yield an end-product, which in some instances contains as much as 90 per cent of protein precipitable by the homologous type-specific polysaccharide.…”