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The characteristic purple colour formed by N-formyl-N'-2,4-dinitrophenyl-hydrazine in the presence of piperidine and acetone was made the basis of a new quantitative method for the determination of formyl groups. Samples containing N-formyl groups (up to 0.4mumole) are hydrazinolysed at 97-98 degrees for 1hr. and are dinitrophenylated after the removal of excess of hydrazine. Interference from 2,4-dinitrophenylhydrazine is eliminated by subjecting the dinitrophenylated samples to chromatography on an alumina column. Interference arising from the formation of N-acetyl-N'-2,4-dinitrophenylhydrazine, when determining formyl groups in samples containing acetyl, can be avoided by a paper-chromatographic separation before analysis. A standard procedure is described. The method gives satisfactory results when applied to N-formyl-amino acids. Gramicidin, when analysed by this method, was found to contain 0.89 mole of formyl group/mole for a molecular weight of 1880. The method indicated the absence of formyl groups from lysozyme, a protein known not to contain such groups. Generally, the analytical values obtained by the method are within 100+/-4% of theory. 相似文献
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A new micro method for determination of cholesterol in serum 总被引:6,自引:0,他引:6
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A sensitive and rapid micro determination of glycogen in biological samples has been described. The method is fluoro-enzymic and is based on the conversion of glycogen to 6-phosphogluconate with the enzymes amylo-α-1,4-α-1,6-glucosidase, hexokinase, and glucose-6-phosphate dehydrogenase. The increase in NADPH is measured fluorometrically. As little as 200 ng of glycogen can be determined. 相似文献
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A micro phosphate method 总被引:2,自引:0,他引:2
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A micro method for simultaneous determination of galactosyltransferase and 5''-nucleotidase activities in cell fractions.
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Galactosyltransferase and 5'-nucleotidase were assayed in the same reaction mixture, with ovalbumin as exogenous acceptor of (14-C)galactose and with (3-H)AMP as the substrate for the 5'-nucleotidase assay. The substrates and reaction products of either assay had no significant effect on the activity of the other enzyme. 相似文献
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In many cases before a protein sample can be subjected to analysis by gel filtration, electrophoresis, or immunoelectrophoresis, concentration may be necessary. Some of the commonly used techniques for sample concentration are adsorption on columns, ultrafiltration through cellophane membranes, evaporation of water, absorption by hydrophilic gels, precipitation by salts or organic solvents, and rechromatography. Except for evaporation, all of the other procedures are practical only when the sample size exceeds a few milliliters. Although there is no lower limit on the sample size when evaporation is employed, the resulting increase in salt concentration of the final product is a problem.In this communication we describe a simple technique that is capable of concentrating, severalfold, samples of proteins 25–250 μl in volume. The technique is based on the same principle as ultrafiltration through cellophane membranes. 相似文献
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A quantitative micro method for the estimation of amine oxides 总被引:1,自引:0,他引:1
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Electrophoresis of acidic glycosaminoglycans in hydrochloric acid: a micro method for sulfate determination 总被引:14,自引:0,他引:14
E Wessler 《Analytical biochemistry》1971,41(1):67-69
A rapid and simple method for estimation of the sulfate content of less than 1 μg of acidic glycosaminoglycans is presented. The procedure is based on the fact that the electrophoretic mobility in 0.1 M hydrochloric acid is proportional to the sulfate content of the polysaccharide. 相似文献
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A new spectrophotometric micro determination of vicinal diols 总被引:1,自引:0,他引:1
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