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Biomedical subjects

T Takagi

Publications and source records attributed to T Takagi.

At least 991 records · Page 55Linked to original sources
PubMed1975

Use of octylbenzenesulfonate in place of dodecyl sulfate in SDS-polyacrylamid gel electrophoresis.

Sodium n-octylbenzene-p-sulfonate was successfully used in place of sodium dodecyl sulfate in SDS-polyacrylamide gel electrophoresis. This modification of the usual technique made it possible to scan the polyacrylamide gel for the distribution of the surfactant by measurement of UV absorption. It was found that a band electrophoresed in advance of the complexes formed between protein polypeptides and the surfactant. The band could be observed even in the absence of protein polypeptide, and was ascribed to micelles derived from surfactant added in excess to the sample solution. The complexes were found to be detectable by scanning at 261 nm, usually with better sensitivity than by scanning at 280 nm. Thus, this modification of SDS-polyacrylamide gel electrophoresis is useful both to investigate what is going on in the gel during electrophoresis and to improve the sensitivity of detection by UV scanning of protein complexes.

Benzenesulfonates↗
PubMed1975

Proton magnetic resonance studies of the binding of an anionic surfactant with a benzene ring to a protein polypeptide with special reference to SDS-polyacrylamide gel electrophoresis.

The binding of an anionic surfactant to a protein polypeptide has been studied by the proton magnetic resonance (PMR) technique to form a part of our studies on the principles of SDS-polyacrylamide gel electrophoresis. Sodium 4-(p-butylphenyl) butane-1-sulfonate (CH3-(CH2)3-0-(CH2)4-SO3-Na+) was employed as an anionic surfactant, and reduced and carbosyamidomethylated (RCAM) bovine serum albumin as a typical protein polypeptide. The binding isotherm of the surfactant to RCAM bovine serum albumin was similar to that of sodium dodecyl sulfate (SDS). The surfactant could replace SDS in SDS-polyacrylamide gel electrophoresis without affecting the wellknown mode of spearation of protein bands. These results gave a sound basis for the assumption that the investigation of the complex between a surfactant with a benzene ring and RCAM bovine serum albumin would provide useful knowledge concerning the principles of SDS-polyacrylamide gel electrophoresis. Aggregation of the aromatic surfactant necessarily brings benzene rings together. A benzene ring is a strong source of the ring current effect on chemical shifts in nuclear magnetic resonance (NMR). Chemical shifts of the surfactant in NMR are, therefore, sensitive to whether the surfactant molecules are single-molecularly dissolved or aggregated. Full advantage was taken of the above fact in the present PMR study of the binding of the surfactant to RCAM bovine serum albumin. The chemical shifts of the phenyl and methyl protons both for the single-molecular and micellar aggregated states were estimated from measurements of the shifts as a function of the surfactant concentration. They shifted to a higher magnetic field on micelle formation, due to the increase of the ring current effect. Corresponding measurements for the complex between the surfactant and RCAM bovine serum albumin gave estimates of the chemical shifts of the phenyl and methyl groups of the surfactant bound to the protein polypeptide. They were found to shift to a magnetic field somewhat higher than that for the micellar state throughout the concentration range of the surfactant examined. These results strongly suggest that the surfactant molecules bind to the protein polypeptide in the form of micelle-like clusters, and that PMR of the groups are further influenced by the diagmagnetic effect of the protein polypeptide present as a core. No appreciable change in the mode of binding, corresponding to the steep increase in the amount of binding in the binding isotherm, was observed from the PMR studies. Taking the observed similarity between SDS and the aromatic surfactant in the binding and the gel electrophoresis into consideration, the present results strongly suggest that SDS also binds to protein polypeptides in the form of micelle-like clusters under the conditions of SDS-polyacrylamide gel electrophoreses, and support our "necklace model".

Benzene Derivatives↗
PubMed1975

Binding isotherms of sodium dodecyl sulfate to protein polypeptides with special reference to SDS-polyacylamide gel electrophoresis.

To clarify the mode of interaction between sodium dodecyl sulfate (SDS) and protein polypeptides with special reference to SDS-polyacrylamide gel electrophoresis, the binding of SDS to several protein polypeptides was investigated by the equilibrium dialysis technique. Each of the binding isotherms was characterized by the presence of two phases: an initial gradual increase in the amount of binding to 0.3-0.6 g/g (first phase) and a subsequent steep increase to 1.2-1.5 g/g (second phase). The binding was completed at a concentration of SDS below the critical micelle concentration. Throughout the first and second phases, the isotherms obtained were different for each kind of protein. On the basis of experiments with bovine serum albumin and ribonuclease (EC 3.1.4.22], the isotherms were profoundly affected by the method used for modification of the sulfhydryl groups. The claim of Reynolds and Tanford (Proc. Natl, Acad. Sci. U.S., 66, 1002 (1970)) that the isotherms are virtually identical for many kinds of proteins was not supported by the present data. Changes in the gross and local conformations were examined with reference to the isotherms by measurements of CD spectrum, free boundary electrophoresis, and gel filtration. The results obtained were collectively interpreted based on the model of SDS-protein polypeptide complexes proposed by the present authors (J. Biochem., 75, 309 (1974)).

Amylases↗
PubMed1975

Electrophoretic properties of sodium dodecyl sulfate and related changes in its concentration in SDS-polyacrylamide gel electrophoresis.

Sodium dodecyl sulfate(SDS) in a protein sample solution migrates in SDS-polyacrylamide gel electrophoresis as a band with a mobility higher than those of protein bands. Behind this band, which is mostly composed of SDS micelles, SDS concentration is raised uniformly in a gel column as a result of the retardation effect of the gel matrix on SDS micelles. Electrophoretic patterns of SDS were obtained when SDS was omitted from various portions of the gel electrophoretic system.

Binding Sites↗
PubMed1975

Retarding effect of dodecyl alcohol on polyacrylamide gel electrophoresis of SDS micelles and SDS-protein polypeptide complexes.

Micelles of sodium dodecyl sulfate (SDS) are significantly retarded by the addition of a small amount of dodecyl alcohol to a sample solution in SDS-polyacrylamide gel electrophoresis. The phenomenon can be ascribed to the decrease in charge density due to the incorporation of dodecyl alcohol into SDS micelles. The effect is extended to SDS-protein polypeptide complexes when the amount of SDS micelles is insufficient to accomodate the dodecyl alcohol. A similar effect is likely to occur when SDS-polyacrylamide gel electrophoresis is applied to a sample containing lipophilic materials.

Alcohols↗
PubMed1974

Platelet and plasma fibrinogens are identical gene products.

Human platelet fibrinogen has been shown to be indistinguishable from plasma fibrinogen by a variety of criteria, including subunit composition and cross-linking characteristics as judged by sodium dodecyl sulfate-gel electro phoresis, quantitative amino terminal analysis of fibrin, and the amino acid compositions of fibrinopeptides released from platelet and plasma fibrinogens is products of the same gene or genes.

Amino Acid Sequence↗