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61.
A new theory for the electron transfer by the non-adiabatic process is formulated taking into account the origin shift and the frequency change of the vibration. The resultant formulas are quite similar to those of Jortner (Jortner, J. (1976) J. Chem. Phys. 64, 4860–4867) except that the free energy gap ΔG is used instead of the energy gap ΔE. By applying this theory to the photosynthetic electron transfer, the role of the remarkable temperature dependence of the electron transfer from cytochrome to P+ in Chromatium vinosum and the experimental data were reproduced very well using a small value of the coupling strength in contrast with the previous theory. This implies that proteins play a role to exclude many of the solvent molecules from the region of the electron transfer reaction between the donor and acceptor molecules. The negative activation process in the back electron transfer from Q?A to P+, the very slow back electron transfer from I? to P+ and the solvent isotope effect on the cytochrome oxidation are also successfully explained by this new theory. It is shown that even a qualitative conclusion as to the molecular parameters obtained from the temperature dependence of the electron transfer is different between the present theory and that of Jortner. 相似文献
62.
The Amino Acid Sequence of the Tryptophan-Containing Subunit (α-Subunit) of Bovine Brain S-100 Protein 总被引:2,自引:2,他引:0
Abstract: The tryptophan-containing subunit (α-subunit) of bovine brain S-100 protein was purified from a S -aminoethyl derivative of S-100a protein, and its amino acid sequence was determined. The α-subunit contained 93 residues, including one tryptophan, and had a molecular weight of 10,400. The sequence shows an extensive homology (58% identity) to the sequence of another "tryptophan-free" subunit (β-subunit) found in both S-100a and S-100b protein, and has a calcium binding site characteristic of the "E-F hand" proteins, such as calmodulin or troponin C. The tryptophan residue is located at position 90 which is presumably adjacent to the C-terminal end of the α-helix following the calcium binding loop, and thus appears likely to serve as a specific probe in structure-function studies of S-100a protein. 相似文献
63.
Mitsumasa Haruna Makiko Kato Kazuo Ito Toshiaki Nikai Hisayoshi Sugihara Hiroyuki Muratat 《Phytochemistry》1981,20(11):2583-2584
Angeloylcumambrin-B, a new antimicrobial guaianolide sesquiterpene lactone, was isolated from Chrysanthemum ornatum and the structure was determined by a combination of chemical and physical methods. 相似文献
64.
Teruyoshi Marunaka Toshiaki Shibata Yoshinori Minami Yukihiko Umeno 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1980,183(3):331-338
A high-performance liquid chromatographic method was developed for the simultaneous determination of phenylbutazone and its metabolites, oxyphenbutazone and γ-hydroxyphenylbutazone, in plasma and urine. Samples were acidified with hydrochloric acid and extracted with benzene—cyclohexane (1:1, v/v). The extract was redissolved in methanol and chromatographed on a μBondapak C15 column using a mobile phase of methanol—0.01 M sodium acetate buffer (pH 4.0) in a linear gradient (50 to 100% methanol at 5%/min; flow-rate 2.0 ml/min) in a high-performance liquid chromatograph equipped with an ultra-violet absorbance detector (254 nm). The detection limit for phenylbutazone, oxyphenbutazone and for γ-hydroxyphenylbutazone was 0.05 μg/ml.A precise and sensitive assay for the determination of phenylbutazone and its metabolites was established. 相似文献
65.
A strategy suitable for the synthesis of larger peptides is proposed. It involves the following four considerations: (1) all of the side-chain functional groups are protected by benzyl-type protective groups; (2) a water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide, is used for the fragment-condensation reactions together with 1-hydroxybenzotriazole as the additive; (3) all the protective groups are cleaved simultaneously by the HF method in the final stage of the synthesis; and (4) side products formed are detected and removed by an efficient high-performance liquid chromatography procedure. The usefulness of these procedures is demonstrated taking the synthesis of human parathyroid hormone [hPTH(1–84)] as an example. 相似文献
66.
NAD recycling in the collagen membrane was investigated as follows: (1) Alcohol dehydrogenase and lactate dehydrogenase were co-immobilized in the collagen membrane and the rate of lactate production by immobilized enzymes was compared with that of free enzymes by using free NAD. An increased rate was observed in the case of immobilized enzyme. (2) The soluble high molecular weight derivatives of NAD (dextran-NAD) were immobilized in the collagen membrane with the two dehydrogenases and recycling of dextran-NAD in the membrane was examined. Lactate was produced by the membrane without adding free NAD. The interaction between the high molecular weight NAD derivatives and enzymes are also discussed. 相似文献
67.
3′,4′-Dideoxykanamycin B, the kanamycin B derivative that is active against resistant bacteria, was prepared from kanamycin B viaN-tosylation, 3′,4′-O-sulphonylation, 3′,4′-unsaturation, and hydrogenation. The unsaturated intermediate was obtained from the 3′,4′-di-O-sulphonyl derivatives by the action of sodium iodide in N,N-dimethylformamide; if zinc dust was added in this reaction, aziridine derivatives were formed, Removal of the tosyl group was successfully performed by using sodium in ammonia-ethylamine. 相似文献
68.
The labeling of sialidase-treated, human erythrocyte membranes with ferritin-conjugates of four plant lectinss, concanavalin A, Ricinus communis hemagglutinin, Bauhinia purpurea hemagglutinin and Arachis hypogoea hemagglutinin, is reported. Among these ferritin-conjugated lectins, ferritin-conjugated concanavalin A and ferritin-conjugated R. communis hemagglutinin were found in clusters on the sialidase-treated membranes, whereas ferritin-conjugated B. pupurea hemagglutinin and ferritin-conjugated A. hypogoea hemagglutinin were found in a random distribution on the membranes. Furthermore, when the membranes were labeled with a mixture of concanavalin A and ferritin-conjugated B. purpurea hemagglutinin, ferritin particles were found in clusters, indicating that the membrane receptors for B. purpurea hemagglutinin were forced to move together with those for concanavalin A. A method for thentitative estimation of the clustering of ferritin particles on the membranes was also devised and applied to the labeling of sialidase-treated, human erythrocyte membranes with the above four ferritin-conjugated lectins. 相似文献
69.
The Clark model for melanoma progression emphasizes a series of histopathological changes beginning from benign melanocytic nevus to melanoma via dysplastic nevus. Several models of the genetic basis of melanoma development and progression are based on this Clark’s multi-step model, and predict that the acquisition of a BRAF mutation can be a founder event in melanocytic neoplasia. However, our recent investigations have challenged this view, showing the polyclonality of BRAF mutations in melanocytic nevi. Furthermore, it is suggested that many melanomas, including acral and mucosal melanomas, arise de novo, not from melanocytic nevus. While mutations of the BRAF gene are frequent in melanomas on non-chronic sun damaged skin which are prevalent in Caucasians, acral and mucosal melanomas harbor mutations of the KIT gene as well as the amplifications of cyclin D1 or cyclin-dependent kinase 4 gene. Amplifications of the cyclin D1 gene are detected in normal-looking ‘field melanocytes’, which represent a latent progression phase of acral melanoma that precedes the stage of atypical melanocyte proliferation in the epidermis. Based on these observations, we propose an alternative genetic progression model for melanoma. 相似文献
70.
Toshitsugu Fukumaru Hiroshi Awata Noritaka Hamma Toshiaki Komatsu 《Bioscience, biotechnology, and biochemistry》2013,77(2):519-527
The synthesis of novel acetylenic ketone compounds and anti-inflammatory and antimicrobial activities are herein described. 相似文献