High Molecular Weight Acid Research Articles

Exopectic Acid Transeliminase of anErwinia

A species of Erwinia was found to produce no other pectolytic enzyme than the two transeliminases of exo-types, namely, an oligogalacturonide transeliminase and an exopectic acid transeliminase. Of the two enzymes, the exopectic acid transeliminase was isolated and its properties were investigated. The results are as follows: (1) Pectic acids having an unsaturated galacturonic acid residue at the non-reducing end of the molecule are susceptible but oxidized or reduced pectic acids resistant to the enzyme action. (2) The enzyme has no activity toward pectinic acid and polymethylpolygalacturonate methyl glycoside. The limit of the enzymatic degradation for citrus pectic acid is 43.8%. (3) The rate of the enzyme activity was maximal with tetragalacturonic acid and followed by acid-soluble pectic acid, acid-insoluble pectic acid, pectic acid and trigalacturonic acid. Unlike the oligogalacturonide transeliminases of Pseudomonas sp. (strain S2) and Erwinia aroideae, the present enzyme shows a considerably high activity toward pectic acids of high molecular weight. (4) The pH-activity curves vary with the buffer employed. (5) The enzyme is activated by Co2+ and Mn2+ but powerfully inhibited by Cu2+ and Hg2+. Ca2+ has no significant effect on the enzyme activity.

Structure formation and heat-hardening of greases

1. Using an instrument for determining ohmic and polarization resistance and an instrument for measuring the electron work function, studies have been made of the polar and electron-acceptor properties of Li, Na, and Ca soaps of various organic acids. Relations have been established among the polar properties of the soaps, the process of their micelle formation, and the bond energies in the disperse system. 2. Li soaps possess a high polarity in the process of micelle formation in the presence of water, as do soaps of 12-hydroxystearic acid and low molecular weight acids such as lauric and palmitic. Correspondingly, these soaps have high bond energies between the anionic and cationic parts of the molecule, between molecules in the micelles, and between the micelles themselves (fibers of the soap). Greases made from such acids are resistant to polarization by external factors and are not prone to heat-harden. 3. Na and Ca soaps possess low polarities, as do soaps of high molecular weight acids such as behenic. These soaps are readily polarized; in the process of heat-hardening, losing their water of solvation, they create an overall ionic system with a high internal energy. 4. Hypotheses have been formulated for the effect of water on the processes of heat-hardening and for the moisture-hardening of various greases. It has been shown that soaps with optimum polarity must be used in order to obtain high-quality greases.

Relationship between low- and high-molecular-weight acids in complex calcium greases based on soaps of synthetic fatty acids

1. The properties of cCa greases based on both narrow and especially wide SFA fractions depend less on the molar ratio of the low- and high-molecular weight acids than for cCa greases based on soaps of individual carboxylic acids. The optimum molar ratio of HAc to the narrow SFA fractions is approximately 2∶1 while for wide C10–C20 SFA fractions it is 1.5∶ 1, which is lower than for individual carboxylic acids (3∶1). 2. A cCa soap of SFA fractions has a reduced thickening effect compared with the soaps of individual carboxylic acids. They surpass the greases thickened with the cCa soap of individual carboxylic acids in a number of properties (viscosity-temperature behavior, colloidal stability). Both wide and narrow SFA fractions are promising raw materials for preparing cCa greases.

Method for Gas Chromatographic Analysis of Fatty Acid Composition of Glycerides Containing Short-Chain Fatty Acids

n-Propylester method was studied to establish a simple and convenient method for gas chromatographic determination of fatty acid composition of fats and oils, such as butter fat, containing both low and high molecular weight acids. The conditions of the preparation of propylesters were examined with the mixtures of butyric and capric acids. It was found that the following procedure was appropriate to prepare the propylesters for GLC analysis.0.25g of acids and 1.25g of alcoholysis reagent (0.3% sodium in n-propyl alcohol) were placed in a 100ml volumetric flask and the mixture was gently agitated at room temperature for 5 minutes. Then the flask was filled up with 20% aqueous solution of sodium chloride to separate ester, and after vigorous shaking the mixture was allowed to stand at 40°C. Propylesters were obtained with a small amount of propyl alcohol as an upper layer.This procedure was further applied to triglycerides containing low molecular weight acids and the results were satisfactory.

〔83〜84〕ポリアミド-イミド類の合成に関する研究

Aromatic polyamic acid of high molecular weight was obtained by the reaction of 4chloroformyl phthalic anhydride with 4, 4′-diaminodiphenyl methane in the presence of acid acceptor in non-basic, polar, and aromatic solvents having poor solubility of water, such as acetophenone, benzonitrile, and nitrobenzene, in anhydrous system. The molecular weight was comparable to that of the polymer obtained from the solution polymerization in anhydrous dimethylacetamide.

Cyclopolycondensation. XII. Polymerization mechanism of polybenzoxazinones in polyphosphoric acid medium

AbstractThe polymerization mechanism of polyphosphoric acid (PPA) solution polymerization of an aromatic diaminodicarboxylic acid with aromatic dicarboxylic acid derivatives was studied. By means of NMR methods, the initiation process for the polymerization of polybenzoxazinone in PPA medium was elucidated. The NMR spectra of a series of compounds were taken, and the salt formation of amino groups of monomer with PPA and the equilibrium between the salt and the free amino group were determined. It was established that the polymerization proceeded through the formation of phosphorylated intermediates to give the salt of amino groups of monomer with PPA. In the second step, the amine–PPA salt dissociates into the free amino group and PPA at the polymerization temperature above 140°C. Polymerization proceeds through the attack of “free” amino on phosphorylated carbonyl compounds to form polyamide acid of high molecular weight, and on subsequently being heated in PPA at higher temperatures, it undergoes an intramolecular cyclodehydration along the polymer chain to form polybenzoxazinones.

Characteristics of the RNA synthesized in vitro by the normal human small lymphocyte and the changes induced by phytohemagglutinin stimulation.

These studies demonstrate that the circulating human small lymphocyte synthesizes ribonucleic acid (RNA) of high molecular weight which is not primarily a ribosomal precursor and which is, in part, complementary to human deoxyribonucleic acid (DNA). The stimulation of these lymphocytes by PHA brings a cell population in which few ribosomes are synthesized to a functional condition in which a large amount of these particles are produced. This increase in the synthesis of ribosomal RNA is one of the earliest and most relevant effects of PHA on the RNA metabolism of small lymphocytes.

Cyclopolycondensations. VIII. New Thermally Stable Aromatic Polybenzoxazinones by Solution Polymerization in Polyphosphoric Acid

Abstract High molecular weight polybenzoxazinones have been prepared by cyclo-polycondensation reaction of 4,4′-diamino-3,3′-biphenyldicarboxylic acid with a variety of aromatic carbonyl compounds using a solution polymerization technique in polyphosphoric acid. From the model reactions of anthranilic acid, and 4,4′-diamino-3,3′-biphenyldicarboxylic acid with benzoyl chloride in polyphosphoric acid, it is established that the cyclopolycondensation proceeds through the formation of an open-chain tractable precursor, polyamic acid of high molecular weight (ninh = 2.66) in the first step, which subsequently undergoes thermal or chemical cyclodehydration along the polymer chain, to yield, in the second step, a fully aromatic polybenz-oxazinone. Polybenzoxazinones thus obtained have excellent thermal stability both in nitrogen and in air. The optimum polymerization conditions for obtaining polyamic acid of high molecular weight are determined by the study of reaction variables such as polymerization temperatur...

Cyclopolycondensations. VI. Fully aromatic polybenzoxazinones from aromatic poly(amic acids)

AbstractNew high temperature aromatic polybenzoxazinones of high molecular weight have been prepared by the cyclopolycondensation of 4,4′‐diaminobiphenyl‐3,3′‐dicarboxylic acid (I) with aromatic dicarboxylic acid halides (II). The low temperature solution polymerization techniques afforded poly(amic acid) (III) of high molecular weight in the first step. An open‐chain precursor subsequently underwent thermal cyclodehydration along the polymer chain at 200–350°C. in the second step, to give in quantitative yield a fully aromatic polybenzoxazinone (IV) of outstanding heat stability both in nitrogen and in air. The poly(amic acid) is soluble in N‐methyl‐2‐pyrrolidone, and tough, transparent films can be cast from solution. Insoluble aromatic polybenzoxazinone films which possess excellent oxidative and thermal stability were obtained by the heat treatment of the polyamic acid. A detailed account of polymerization conditions in the low temperature solution polymerization of polybenzoxazinones is given, and the reaction mechanisms of cyclopolycondensation of poly(amic acids) and the formation of polybenzoxazinones are discussed.

Cyclopolycondensations. III. Solution polymerization of aromatic diaminodicarboxylic acid in polyphosphoric acid

AbstractPolyamide amino acids of high molecular weight were prepared by the self‐polycondensation of aromatic diaminodicarboxylic acids in polyphosphoric acid. Polyamide amino acids thus obtained were converted to the fully aromatic polymer containing benzoxazinone rings by the cyclodehydration in polyphosphoric acid. The resulting aromatic polymer shows excellent thermal stability up to 450°C in nitrogen. The fully aromatic heterocyclic polymers were characterized by good thermal stability and the molecular weight attained was high enough to exhibit film‐forming properties for the products.

End-group labeling of nucleic acids by enzymatic phosphorylation.

End-group analysis has proved to be a valuable technique for determining the homogeneity, molecular weight, and amino acid sequence of proteins (Sanger, 1952). End-group analysis of nucleic acids can provide similar information about these macromolecules. Although a number of techniques for end-group analysis of nucleic acids are now available, their usefulness has been limited. First, successful application of the technique depends upon the availability of homogeneous nucleic acid preparations; second, the method employed must be sensitive and quantitative; and third, the procedure used for analysis must not introduce extraneous end-groups. These considerations become increasingly important in the study of naturally occurring nucleic acids of high molecular weight.

Preservation of rapidly synthesized ribonucleic acid of high molecular weight in frozen nuclei of rat liver

Preservation of rapidly synthesized ribonucleic acid of high molecular weight in frozen nuclei of rat liver

Chemical changes of synthetic fatty acids during rectification under industrial conditions

1. The chemical conversions which accompany the rectification of raw synthetic fatty acids and result in a loss of the fractions suited for soap manufacture are the most intensive in the boilers of the fourth and fifth columns. 2. During rectification of synthetic fatty acids under a rigorous regime, the weight-average of the acid number drops by 10–15% and the content of unsaponifiable substances is doubled or more than doubled, as is the content of resins. The changes of the carbonyl and the acid numbers pass through a maximum. 3. Synthetic fatty acids of high-molecular weight are sufficiently stable during heating to 320°C in 3–8 min and during rapid overheating of the feeds to the fourth and fifth columns (310–320°C); rapid overheating decreases the degree of thermal decomposition during rectification by almost 50% and increases the yield of acids suited for soap manufacture by 6.1%.

Spontaneous degradation of aromatic polypromellitamic acids

The reaction of pyromellitic dianhydride with a solution of a primary diamine in a solvent such as dimethylacetamide gives a viscous solutionof a polypyromellitamic acid of high molecular weight. The viscosity of the solution decreases greatly when it is aged at 35°C. Higher temperatures or the presence of water, excess amine or excess anhydride accelerate the rate of decline. A rapid early drop in viscosity has been found to be due primarily to hydrolysis by adventitious water and to exchange reactions of amine or anhydride groups with the o-carboxyamide linkage. Slow decline over a long period of time results from hydrolysis by water produced in the slow conversion of polypyromellitamic acid to polypyromellitimide. Degradation by hydrolysis also occurs when polyimide films are cast by heating the solution. The effect can be minimized by casting thin films, from which water can diffuse rapidly, or by using a chemical method, such as treatment with acetic anhydride and pyridine, to remove the water produced in imidization.

Chromatography of ribonucleic acid of high molecular weight isolated from FL cells infected with ECHO 7 virus

Chromatography of ribonucleic acid of high molecular weight isolated from FL cells infected with ECHO 7 virus

Interaction of acids of high molecular weight with albumin.

Interaction of acids of high molecular weight with albumin.

Formation of silicotic tissue.

ELECTRON micrographs of normal connective tissue reveal a very fine protein network superimposed on a much coarser network1. The interstices are filled with protofibrils and mucopolysaccharidic acids of high molecular weight. Fibrous connective tissue is produced when lung tissue is degenerated by silica particles, the silicic acid formed by the dissolution of the silica probably being involved, and the possible analogy between the role of silicic acid and that of the mucopolysaccharides is evident.

The Inhibition of Fusarium oxysporum var. cubense by Musarin, an Antibiotic produced by Meredith& apos;s Actinomycete

SUMMARY: Under selected conditions Meredith's actinomycete produced culture fluids toxic to many fungi. From these fluids the active principle, called musarin, has been isolated by two methods. Preparations active in concentrations of 1/80,000--1/100,000 seemed substantially pure. Musarin is an optically active acid of high molecular weight having by microtitration an equivalent weight of at least 4000. Analyses of the best preparations are in good agreement with an empirical formula (C35H60O14N2)72. No definite conclusion can be drawn about the exact chemical nature of musarin; a protein-like structure seems to be excluded by the low nitrogen content, which recalls that of many bacterial polysaccharides; but formulation as a polysaccharide seems equally unsatisfactory because of the low oxygen content. Tests indicate that musarin is one of the most potent antifungal antibiotics, though as an antibacterial agent it is less effective. It is active against several important plant parasites and it may be useful in combating the Panama disease of the banana plant and other fungal diseases of economic importance.

The Isolation of β-Amyrin and a Fatty Acid of High Molecular Weight from Solidago leavenworthii T. and G.

The Isolation of β-Amyrin and a Fatty Acid of High Molecular Weight from Solidago leavenworthii T. and G.

Mosquito repellents

Mosquito repellents