Showing papers on "Buffer solution published in 1976"

Studies on phenylpyruvic acid. I. Keto-enol tautomerism.

Abstract: The tautomerism of phenylpyruvic acid (PPA) and its sodium salt was investigated. The 1H and 13C spectra of PPA in aprotic solvents and in methanol show almost complete prevalence of the enol form, whereas the keto form prevails only in water. The Z configuration was assigned to the sole enol tautomer present on the basis of the value of the vicinal coupling constant [3J1H, 13COOH]=3.7 Hz. A small amount of the hydrated form of PPA (1-phenyl-2, 2-dihydroxylpropanoic acid) was found in the aqueous solution of its sodium salt and in buffer solution (pD=6) of PPA. By means of infrared spectroscopy one can conclude that crystalline PPA is in the enol whereas its sodium salt is in the keto form. The keto-acid was not obtained in the solid state. The colorimetric method for testing PPA traces in urine depends on the formation of a enol-Fe3+ complex (2:1) which appears stable in dimethylsulfoxide (DMSO).

Assay of isoenzymes by ion exchange chromatography

Abstract: A simple, rapid anion-exchange column chromatographic technique is used to determine the presence of fractions of proteins and enzymes in human serum by separating the fractions on the basis of their net electrical charges. Samples of serum of unaltered ionic strength, layered on mini columns of an ion exchange agent previously equilibrated to a low ionic strength similar to blood serum with a buffer solution, are eluted stepwise with an appropriate buffer solution having different ionic strengths at each step. Elution of the samples is without previous dialysis or other ionization treatment. Column effluents are assayed for protein content or enzyme activity by conventional means, e.g., spectrophotometric analysis. Evaluation of sera from patients utilizing these methods reveals protein fractions or isoenzyme patterns which identify specific diseases associated with the protein or isoenzyme pattern.

Tube gel electrophoresis device

Abstract: A device for performing electrophoretic separation of samples in a tube shaped gel. An outer container has an open upper end and side walls joined by a bottom closure. An upper buffer chamber assembly is received in and supported by the open upper end of the outer container. The upper buffer assembly defines an upper buffer chamber therein having a bottom wall spaced from the bottom closure of the outer container and thereby together with the outer container sidewalls forming a lower buffer chamber. A removable cooling core is disposed in the lower buffer chamber and has a cooling passage therethrough having open ends in communication with the lower buffer chamber. A plurality of tubes for holding electrophoresis separation gels are provided which extend through the bottom wall of the upper buffer chamber, thereby having one end in communication with each of the upper and lower buffer chambers. An electrode is provided in each of the buffer chambers so that when buffer solution is contained in each buffer chamber and voltage is impressed across the electrodes, the sample is electrophoretically separated in the separation gel in the tubes and heat energy generated within the separation gels is passed to the buffer solution in the lower buffer chamber. Circulation of the buffer solution through the cooling passages in the cooling core in turn transfers the heat energy to a coolant passing therethrough.

Properties of Monomeric Paramyosin Using Transient Electric Birefringence Techniques

Abstract: Paramyosin samples obtained from the chowder clam, Mercenaria mercenaria, by different extraction techniques were studied using transient electric birefringence techniques. The protein remain monomeric (unaggregated) in 1 mM buffer solution at pH 3.1 to 3.8 and near pH 10. At pH 3.2, the molecules obtained by different extraction techniques exhibit rotational diffusion constants that indicate a 5% difference in length between them, with the probable native form of paramyosin being the longer species. This difference in rotational diffusion constant disappears at higher pH, and, in addition, a large difference in dipole moment between the molecules observed at pH 3.2 also disappears at high pH. These results are used to hypothesize that the rodlike native paramyosin molecules have one or two partly flexible portions on their ends; at one end of each molecule this portion probably contains excess basic amino acids which are charged at low pH to account for the higher dipole moment of this form of paramyosin at these low pH values. At pH 3.2, these portions of the macromolecule are not flexible and act as stiff parts of the rodlike molecules, but they gradually become flexible at higher pH. Possible mechanisms for this change in flexibility are discussed.

Differential Behaviour of Molecular Species of β-1, 3 Glucanase of Some Bacterial Glucanase Systems on Avicel Columns

Abstract: When crude culture fluid of an Arthrobacter bacterium was applied on to Avicel column equilibrated with 0.01 m phosphate buffer, pH 6.8, lytic activity for isolated yeast cell wall adsorbed to the column and was eluted from the column by successive washing with the same buffer solution. Examination by disc electrophoresis revealed that the molecular species of β-1,3 glucanase with high lytic activity for isolated yeast cell wall were the main protein components of the pooled active fractions. These molecular species adsorbed to Avicel column also in 0.01 m succinate buffer, pH 5.6, but did not in 0.01 m Tris chloridez buffer, pH 8.5. The molecular species of β-1,3 glucanase with low lytic activity for isolated yeast cell wall did not show any appreciable adsorption to Avicel column under the conditions tested. Two molecular species of β-1,3 glucanase with high lytic activity for isolated yeast cell wall of a strain of Bacillus circulons adsorbed to Avicel column in 0.01 m succinate buffer, pH 5.6 and in 0...

Method for obtaining urokinase

Abstract: A method for obtaining urokinase which comprises steps of contacting a partially purified urokinase-containing solution with diatomaceous earth at a pH range of 4.0 - 8.0, washing said diatomaceous earth adsorbing urokinase thereon with a buffer solution of pH 6.5 - 9.0 and eluting the urokinase from the adsorbate.

Electrochemical reduction of benzaldehyde to benzyl alcohol at a mercury cathode

Abstract: On the example of the electroreduction of benzaldehyde it was shown that it is theoretically possible to obtain the alcohol in quantitative yield by suppressing the formation of pinacols; for this it is necessary to use low concentrations of benzaldehyde and high concentrations of a potassium salt in the buffer solution with a pH of 6.0–6.5 at potentials of −2.0 V (relative to the satd. calomel electrode).

Acid-base reactions in nitromethane

Abstract: 1. Study has been made of electrode systems in nitromethane. Constancy of the liquid potential has been proved for certain reference electrodes. The glass electrode has been shown to have a hydrogen function in nitromethane solutions. 2. Buffer solutions based on picric acid and its salts, diphenylguanidine picrate and tetrabutylammonium picrate, have been used to calibrate electrode pairs. Dissociation constants for these salts have been determined, spectrophotometrically and conductometrically. The buffer solution pH's have been calculated, allowance being made for incomplete salt dissociation.