Phosphate-citric Acid Buffer Research Articles

Nitrosymmetallochelates—I. Mechanism of FeNO—EDTA complex formation and its oxidation

A nitrosyliron(II) complex with EDTA was produced by reaction of the Fe(II)—EDTA complex and nitrous acid in citric acid—phosphate buffer solution. The experimental results pointed out that nitrous acid is reduced to nitrous oxide by Fe(II)—EDTA complex followed by the formation reaction of nitrosyliron(II) EDTA complex. The composition of this complex was determined to be Fe(II) (NO) 2EDTA by both electrochemical and spectroscopic methods. A mechanism of the oxidation of Fe(II) (NO) 2EDTA was proposed in which nitrous oxide breaks away from the iron ion. The photoeffect on this reaction is discussed.

Surface Topography of Blank-Dyed Merino Wool

Merino wool was blank-dyed in citric acid-phosphate buffer at pH 2.0, 4.5, and 8.0, at the boil, for periods of up to five hours. The treatment dissolved significant quantities of protein material from the wool and altered the fiber cuticle surface. Scanning electron microscope studies showed that modification of the cuticle cell surface occurred at all pH's, with the most severe disruption of the surface being at pH 2.

Effect of storage time and temperature on the survival of Clostridium botulinum spores in acid media.

Clostridium-botulinum type A and type B spores were stored in tomato juice (pH 4.2) and citric acid-phosphate buffer (pH 4.2) at 4, 22, and 32 degrees C for 180 days. The spore count was determined at different intervals over the 180-day storage period. There was no significant decrease in the number of type A spores in either the tomato juice or citric acid-phosphate buffer stored for 180 days at 4, 22, and 32 degrees C. The number of type B spores did not decrease when storage was at 4 degrees C, but there was an approximately 30% decrease in the number of spores after 180 days of storage at 22 and 32 degrees C.

Is the Stimulation of Sugar Transfer by Exogenous ATP a pH effect?

By means of perfusion techniques sucrose, alone or in combination with ATP, ADP, and buffer solutions, was supplied exogenously to the cells surrounding the xylem in tomato internodes. ATP (pH 3.4) and citric acid-phosphate buffer (pH 3.4) enhanced the uptake of sucrose to the same extent. ADP (pH 4.8) produced 60% less effect. A citric acidphosphate phosphate buffer (pH 6.5) neutralized the promoting effect of ATP. All results point to a promoting effect of the low pH rather than of ATP on the uptake of sucrose.

Preparative cell electrophoresis.

Abstract A simple method is described for preparative cell electrophoresis. Solid glass beads (≃ 0.1 mm diameter) are used as packing material in a cylindrical glass column, the interstices of which contain a citric acid-phosphate buffer of pH 7.6 and 0.015 ionic strength. Cell mixtures containing ≃ 6 × 109 erythrocytes in 0.2 ml are electrophoresed at 25 V/cm for 1–2 hours after which the column contents are extruded and the separated cell fractions recovered. Complete separation was achieved between mixtures of human and chicken erythrocytes and untreated and papain-treated human erythrocytes. The electrophoretic mobilities of cells subjected to this procedure are in good agreement with previously published mobilities, obtained by microelectrophoresis.

Leukocyte β-Galactosidase Activity in GM1-Gangliosidosis

The recent article by Singer et al. entitled "Leukocyte beta-Galactosidase Activity in the Diagnosis of Generalized GM1-Gangliosidosis," prompts us to report the results of two years of routine service assay of this enzyme in leukocytes using the alternative substrate, 4-methyl-umbelliferyl β-D-galactopyranoside. The β-galactosidase assay medium contained McIlvaine phosphate-citric acid buffer, pH, 4.1 (40µl); 4-methylumbelliferyl β-D-galactopyranoside (1 mM in buffer, 150µl) and leukocyte extract in 0.2 MKCl (10µl). After incubation for 15 minutes at 30°C, the reaction was stopped by the addition of 0.25 M glycine-NaOH, pH, 10.4 (1 ml) and the fluorescence measured.

An improved histochemical method for the demonstration of disaccharidases with natural substrates.

A simple histochemical method for the demonstration of disaccharidases is described. The medium consists of natural disaccharides (as substrates) and glucose oxidaseperoxidase-3,3′-diaminobenzidine tetrahydrochloride (as the detecting agent) buffered to pH 6.0 with 0.05 M citric acid phosphate buffer in 1/2% agar gel. This method which enables the localization of disaccharidases on the histological level is very suitable for the routine assessment of activities of disaccharidases in enterobiopsies.

Quinacrine fluorescence of the human Y chromosome.

RECENT observations1–4 of specific localized fluorescence in Y chromosomes stained with quinacrine mustard and quinacrine hydrochloride have provided a new parameter for the study of abnormal Y chromosomes. We have re-examined regularly prepared chromosome and buccal smear slides of at least 100 cells from two patients with a small Y chromosome5 and from patients with normal Y chromosomes. We used a modification of techniques described earlier1–4. We stained for 5 min in 0.5% quinacrine hydrochloride (Winthrop); washed in distilled water; differentiated for 3 min in citric acid-phosphate buffer, pH 5.5; washed and mounted slides in phosphate buffer, pH 7.4, and sealed with nail polish. Preparations were examined with a Leitz Ortholux microscope with a mercury arc lamp, standard fluorescence filters, and dark-field illumination, and were photographed with Ektachrome high speed film. Fluorescence persisted for several days. Full details of the technique will be published later.

Complexometry of sodium hydrogen phosphate-citric acid (buffer)-ascorbic acid system

Complexometry of sodium hydrogen phosphate-citric acid (buffer)-ascorbic acid system

界面活性剤による鮮魚の細菌除去に関する研究

1. The cleaning effect on jack mackerel (Trachurus trachurus) was examined with different surface active agents, such as sodium linear alkylbenzene sulfonate (LAS), sucrose fatty acid ester (SE), and polyoxyethylene (9) fatty alcohol (C16-18) ether (PEFA). The surface active agents were dissolved in phosphate-citric acid buffer of different pH values. 2. Cleaning of fish with PEFA and LAS at pH 5.0 resulted in a clean surface appearance and the removal of unpleasant fishy odour. But the skin surface treated with LAS turned buff colour within 1-2 days after cleaning. 3. Viable bacterial counts on the skin surface decreased to 1/100-1/1000 after cleaning with PEFA solution at pH 5.0. No other surface active agents tested showed similar effect.

Zum Wirkungsmechanismus von 1-Nitroso-3-nitro-1-methylguanidin (NNMG) bei der Mutationsauslösung / The Mode of Action of 1-Nitroso-3-nitro-1-methyl-guanidine (NNMG) in Mutagenesis

1. The stability of NNMG with respect to pH was investigated. A maximum, with a half-life of 40 hours, was found in phosphate-citric acid buffer at pH 5. The stability decreases quickly with increasing concentration of hydroxyl ions. At the optimal mutation rate (pH 6, 37°, and shaking) the half-live is only 14,4 hours. 2. NNMG uptake (using labelled NNMG) and mutation rate in the range pH 3,5 — 8,0 show an optimum at pH 6,0/6,5 for both Escherichia coli B and the red ad- mutant E 188 of Saccharomyces cerevisiae. The pH-dependence of NNMG uptake and mutation rate is similar. 3. The methylation of nucleic acids by means of [3H]-methyl-NNMG or [14C] -methyl-NNMG in phosphate-citric acid at 37° while shaking increases with the growing concentration of hydroxyl ions. At the optimal mutation rate, however, NNMG methylates relatively poor. 4. Incorporation of radioactive NNMG into Escherichia coli B results in labelling of nucleic acids and proteins. The labelling of DNA shows an optimum at pH 6. The extent of methylation was found to be higher in vivo than in vitro. 5. In the presence of cysteine or β-mercaptoethanol nucleic acids are methylated more intensively than in the cysteine-free control experiment. After one hour the methylation was about twentyfold higher in the presence of cysteine or β-mercaptoethanol compared to the cysteine-free control experiment. The methylation in presence of SH-compounds shows a maximum at pH 6. The explanation of both a higher methylation rate and its optimum at pH 6 suggests the activation of methylation by means of sulphhydryl-groups.

Studies on the Auxin Metabolism of Some Cereal Crops under Germination and Seedling Growth : I. Some characteristics of IAA-oxidizing enzyme existing in wheat seedlings.

Some characteristics of IAA-oxidizing enzyme existing in dark-grown wheat seedlings were studied, and the results obtained were summarized as follows: After demonstrating the existence of IAA-oxidizing action in dark-grown wheat seedlings, the crude- and dialyzed homogenates were prepared from root, coleoptile and plumule. Then, their IAA-oxidizing and guaiacol-peroxidizing activities were determined and compared with each other. The dialysed enzyme preparation from wheat seedlings showed a considerably high IAA-oxidizing activity. Descending order of this enzyme activity was root, coleoptile and plumule, and pH 4.5, 5.0, and 5.5 were the optimum pH value in root, coleoptile and plumule respectively. Similar results were obtained in the activity of peroxidase from the same source. There was, however, a eminent difference between the crude and dialysed enzyme preparation in the mode of action that the crude enzyme preparation is lacking in IAA-oxidizing activity in spite of its high peroxidase activity. It may be, therefore, concluded that the lack of IAA-oxidizing activity of the crude preparation is due to the existence of some dialysable, heat-stable inhibitors in the preparation. In order to clarify the caracteristics of IAA-oxidizing enzyme furthermore, the authers have undertaken some experiments and obtained the following results. IAA-oxidizing activity of the dialysed preparation was inactivated by heat-treatment as the exactly same as the activity of peroxidase in the same preparation, and IAA-oxidizing activity of the crude preparation was considerably promoted by addition of both Mn++ and DCP, while the activity of the dialysed preparation was inhibited by added Mn++ and was promoted by added DCP. In the mode of inhibitory action of some enzyme inhibitors added, there were considerable differences between IAA-oxidation and guaiacol-peroxidation. A comparatively low concentration, 10-5M of H2O2, showed a little promotion of IAA-oxidizing activity in the dialysed preperation, but the activity was greatly inhibited by a much higher concentration, 10-4M of H2O2, and catalase showed little effect on the activity of the same preparation. From the above-mentioned results, it may be concluded that IAA-oxidizing enzyme existing in dark-grown wheat seedlings is a peroxidase and there are some differences between IAA-oxidation and guaiacol-peroxidation in the reaction mechanism. Furthermore, from the results concerning the effects of catalase and H2O2, it is suggested that IAA may be oxidized by wheat seedling peroxidase through the same reaction mechanism as the scheme presented by YAMAZAKI and SOUZU (1958). ADDENDUM: Since this manuscript went to press, we have noticed that the inhibitory effect of Mn++ on IAA-oxidizing activity in the dialysed enzyme preparation may be due to the chelating effect of citrate in McIlvaine's (phosphate-citric acid) buffer used, and that this phenomenon has been already described in the following papers. Kenten, R. H. 1955. The oxidation of indolyl-3-acetic acid by waxpod bean root sap and peroxidase systems. Biochem. J. 59 : 110-121. Stutz, R. E. 1957. The indole-3-acetic acid oxidase of Lupinus albus L. Plant Physiol. 32 : 31-39.

Studies on Haematoxylin and Haematein, the Colouring Principles of Logwood: I–Absorption Spectra of Pure Compounds in Various Solvents and a Spectrophotometric Method of Analysis for Haematoxylin and Haematein

A modified method is described for the preparation from logwood extracts of pure haematoxylin. The criterion of purity is the ultraviolet absorption spectrum in methanol. In most solvents with low ultraviolet absorption, haematoxylin is either too insoluble or too susceptible to oxidation for suitable spectra to be obtained without special precautions.The salient features of the visible and ultraviolet absorption spectra of haematein (about 10 mg. / litre) in six solvents are given. In most of these haematein is eventually oxidised to give a product with a characteristically different spectrum. Solutions in dimethylformamide containing 1 % of a phosphate–citric acid buffer are sufficiently stable for the haematein content to be determined by reference to the peak at 440 mμ. instead of the previously used peak at 280 mμ., which is shown to be unsuitable.Examples of the application of the analytical method to commercial materials are given.

In vitro studies on the effect of pH and of glucose on ammonia accumulation in the rumen of sheep

The effect of pH and of glucose on ammonia accumulation in rumen liquor, obtained from sheep rumen contents, was studied during 4-hr in vitro incubations. Control of pH over the range 4.5-7.3 was effected with sodium phosphate-citric acid buffer. Casein hydrolysate was added as a substrate for ammonia production. There was an optimum pH for ammonia accumulation which varied between 6.0 and 6 . 7 on different diets, and which appeared to be correlated with the range of pH normally encountered in the rumen on each diet. Ammonia accumulation fell rapidly on the acid side of the optimum pH and usually less rapidly on the alkaline side. This effect of pH is most probably due to an effect on ammonia production, i.e. an effect on deamination of amino acids. Glucose reduced ammonia accumulation to an extent greater than could be accounted for by the fall in pH due to the fermentation of glucose; protein nitrogen levels in the reaction mixture were significantly increased. It was concluded that the effect of glucose was due largely to a stimulation of ammonia utilization for synthesis of microbial protein and not to an inhibition of ammonia production.

The pH-resistance of erythrocytes: II. The influence of electrolytes

The results of the investigations with citric acid-phosphate buffers in haemolysis suggest that a specific influence is exerted by the H+ ions, and thus by the pH of the external medium. This was checked with the aid of pure phosphate buffers, which gave exactly the same results (initial haemolyse: pH 5.1). In this way it could be proved that citrate exercised no anion-effect. A possible cation-exchange of Ca 2+, Mg 2+ and K+ ions for H+ ions in the erythrocyte membrane was investigated by following up the influence of these ions on haemolysis. In contrast to the haemolysis-depressing effect of small quantities of Ca 2+ ions in the osmotic haemolysis, no such influence could be detected in pH haemolysis, but a slight resistance-suppressing influence was detected. It was demonstrated that the Mg 2+ ions greatly suppress haemolysis with decreasing pH. Here too, the initial-haemolysis starts at a slightly higher pH. In the pro-lytic phase of the haemolysis a marked K +-shift from the cells occurs. The extra-cellular K+ concentration rises to very high values with decreasing pH.

ENZYMES OF BARLEY AND MALT II. RAPID PRELIMINARY FRACTIONATION BY SELECTIVE ELUTION FROM ALUMINA

Enzymes of malt which individually bring about the hydrolysis of starch, maltose, panose, sucrose, laminarin, cellobiose and adenosine have been partially purified by gradient elution from an alumina column with phosphate-citric acid buffer; by this means also the fractionation of α- and β-amylase activities has been achieved. Evidence has been obtained for the separation of different enzymes hydrolyzing laminarin, one functioning by stepwise action leading to the production of glucose units and the other by random attack. Additionally, evidence has been obtained for the presence of an enzyme which brings about an increase in the iodine-staining capacity of starch and for the ability of this enzyme or one associated with it to catalyse the fission of α-I-6-glucosidic linkages.

The Thermal Destruction of Riboflavin

The thermal destruction of riboflavin in buffer solutions from pH 0.5 to 12.0 has been studied by ll'teans of fluorimetric analysis and the application of the first-order reaction and Arrhenius equations. The buffer solutions used were a modified universal buffer (phosphate, borate, acetate), McIlvaine's citric acidphosphate buffer, veronal-HCI, and glycine-NaOH.

Observations on the Solubility of Certain Sulfonamides

The solubility of a triple sulfonamide mixture consisting of equal parts of sulfadiazine, sulfamerazine, and sulfamethazine, and of a mixture of equal parts of their N4-acetyl derivatives was determined in the range of pH 4.5 to 7.5 at 37°, utilizing sodium phosphate-citric acid buffer solutions as solvent. The solubility of N1-(3,4-dimethyl-5-isoxazolyl) sulfanilamide and its N4-acetyl derivative was also determined. A comparison of the solubility data is made and is discussed briefly. Details of the experimental and analytical procedures are described.

THE RELATION OF pH AND TEMPERATURE TO THE FRUITING OF PHYSARUM POLYCEPHALUM

American Journal of BotanyVolume 26, Issue 9 p. 709-714 Article THE RELATION OF pH AND TEMPERATURE TO THE FRUITING OF PHYSARUM POLYCEPHALUM William D. Gray, William D. Gray 214 Pearl Street, Jefferson Ville, IndianaSearch for more papers by this author William D. Gray, William D. Gray 214 Pearl Street, Jefferson Ville, IndianaSearch for more papers by this author First published: 01 November 1939 https://doi.org/10.1002/j.1537-2197.1939.tb09342.xCitations: 13AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume26, Issue9November 1939Pages 709-714 RelatedInformation