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31.
Ikeno Takeyuki Hashimoto Seiichi Kuzuya Hiroshi Nagatsu Toshiharu 《Molecular and cellular biochemistry》1977,18(2-3):117-123
1. Two different molecular forms of dopamine-beta-hydroxylase were isolated from human serum; a major component (Peak I enzyme) with a molecular weight of 368000 and with a higher specific activity and a minor component (Peak II enzyme) with a molecular weight of 188000 and with a lower specific activity. 2. Both forms require ascorbic acid for the activity, and are stimulated by fumarate. Addition of N-ethylmaleimide or copper also increased the activity. The optimal pH of both forms in the presence of 20mM tyramine as substrate is 5.0. 3. Km values toward tyramine of Peak I enzyme and Peak II enzyme were 1.67 mM and 14.2 mM respectively. 4. Both Peak I enzyme and Peak II enzyme are glycoprotein. 相似文献
32.
Akihiko Yano Katsuyuki Yui Masuji Yamamoto Fumie Aosai Seiichi Furuta Soumei Kojima 《Microbiology and immunology》1983,27(5):455-463
Peripheral blood leukocytes (PBL) from patients with toxoplasmosis were shown to be highly responsive to in vitro stimulation with Toxoplasma gondii extract as measured by incorporation of [3H]methylated thymidine. Analysis of Toxoplasma-specific proliferative cells in PBL by using monoclonal antibodies specific for human T cell subsets revealed that the Toxoplasma-specific proliferation response of PBL from the patients was mediated by Leu 1, Leu 3a positive cells, that is, helper/inducer T cells. Tests for the Toxoplasma-specific proliferation response may provide a readily available method for the diagnosis of congenital toxoplasmosis, especially during the newborn period. 相似文献
33.
Seiichi Tokura Yoshihiro Ikeuchi Shin-ichiro Nishimura Norio Nishi 《International journal of biological macromolecules》1983,5(4):249
A new type polyamide containing a glucose unit in the main chain has been synthesized by the polymerization of C1, C3, C4 blocked C6-carboxymethylglucosamine, prepared from chitin. The deblocking procedure gave the water-soluble polyamide, of MW 1.5 × 104, which can be regarded as a model for the recognition site of lectin. 相似文献
34.
Five A-U analogues containing deoxyadenosine or 2'-halo-2'-deoxyadenosines, which are known to have widely different C3'-endo conformer populations according to their electronegativities of the halogen substituents, dAfl-U, dAcl-U, dAbr-U, dAio-U, and dA-U, were synthesized chemically. Characterization of these dimers has been performed by UV absorption, circular dichroism, and proton nuclear magnetic resonance spectroscopy. The results show that the dimers containing 2'-halo-2'-deoxyadenosines have stacked conformations with a geometry similar to that of A-U and the degree of stacking decreases in the order dAfl-U greater than dAcl-U greater than dAbr-U greater than dAio-U. dAcl-U is assumed to have the same degree of stacking as A-U. dA-U takes a more stacked conformation than does dAio-U, but the mode of stacking is different from those of the other dimers. The effects of the 2' substituents on dimer conformation are discussed in terms of electronegativity, molecular size, and hydrophobicity. 相似文献
35.
H Ueda H Maruyama M Doi M Inoue T Ishida H Morioka T Tanaka S Nishikawa S Uesugi 《Journal of biochemistry》1991,109(6):882-889
An artificial gene coding for the human cap binding protein (hCBP: human IF-4E) was chemically synthesized and expressed in Escherichia coli under the control of a trp promoter. The DNA duplex of 662 bp was designed and constructed from 44 oligodeoxynucleotide fragments of typically 30 nucleotides in length. Although the hCBP gene was not directly expressed in E. coli HB101, we succeeded in its high-level expression as a fusion protein connected with a portion of human growth hormone through a tetradecapeptide (Asp-Asp-Pro-Pro-Thr-Val-Glu-Leu-Gln-Gly-Leu-Val-Pro-Arg) that contains the recognition sequence for a site-specific protease alpha-thrombin. Upon induction with 3-indoleacrylic acid, the fusion protein accumulated with a yield of about 20% of the total proteins of the host cell. Upon the treatment of the fusion protein with alpha-thrombin, which recognizes the sequence "Val-Pro-Arg," specific proteolysis at the fused junction occurred efficiently. In this system, nonspecific digestion by alpha-thrombin was not marked. About 15 mg of recombinant hCBP was obtained from a 1-liter culture. Association constants between the recombinant hCBP and mRNA cap structure analogues were determined by fluorescence spectroscopy. The values obtained for the m7GpppA, m7GTP, and m7GMP were almost the same as those reported for the IF-4E isolated from human erythrocyte cells.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
36.
T Hakoshima T Itoh K Gohda K Tomita S Uesugi S Nishikawa H Morioka E Ohtsuka M Ikehara 《FEBS letters》1991,290(1-2):216-220
Complex of a mutant ribonuclease T1 (Y4SW) with a non-cognizable ribonucleotide, 2′AMP, has been determined and refined by X-ray diffraction at 1.7 Å resolution. The 2′AMP molecule locates at a new base-binding site which is remote from the guanine-recognition site, where 2′GMP was found to be bound. The nucleotide adopts the anti conformation of the glycosidic bond and C3′-exo sugar pucker. There exists a single hydrogen bond between the adenine base and the enzyme, and, therefore, the site found is apparently a non-specific binding site. The results indicate that the binding of 2′AMP to the guanine-recognition site is weaker than that to the new binding site. 相似文献
37.
The reaction products of methyl thioglycolate with dynemicin A, dynemicin H and dynemicin S, were isolated by HPLC purification and identified spectroscopically. The major product, dynemicin H (C30H23NO9), was determined to be a C-8 hydrogen analogue of dynemicins L and N in which the enediyne core is aromatized. The minor product, dynemicin S (C33H27No11S), is an adduct of methyl thioglycolate at the C-8 position. By using NADPH instead of methyl thioglycolate, the reaction with dynemicin A also gives the same major product (dynemicin H). The nucleotide-specific cleavage of dynemicin A induced by addition of methyl thioglycolate is remarkably similar to that induced by addition of NADPH, whereas dynemicins H and S show no DNA cleavage activities. The formation of dynemicins H and S provides a rationale for the reductive and nucleophilic activations of dynemicin A. 相似文献
38.
The association of two enzymes involved in the shikimate pathway,3-dehydroquinate hydro-lyase (EC 4.2.1.10
[EC]
) and shikimate: NADPoxidoreductase (EC 1.1.1.25
[EC]
), was studied with shoots of etiolated4-day-old Phaseolus mungo seedlings. The enzymes were not separableby ammonium sulfate fractionation, sucrose density gradientcentrifugation, polyacrylamide gel electrophoresis and chromatographyon Sephadex G-100 and DEAE-Sephadex A-50. The results are discussedin relation to the channelling function of metabolites in thealicyclic acid metabolism in higher plants. (Received October 28, 1975; ) 相似文献
39.
40.
Uptake of homologous series of p-n-alkylphenols by fungi from aqueous phase was studied using spores of Piricularia oryzae and Gibberella fujikuroi, and mycelia of P. oryzae as test organisms.Process of uptake seemed to be physical, because dead cells took up as much phenol as did living cells. Amount of phenol taken up by fungal cells equilibrated with concentration of remaining phenol in external aqueous phase. Uptake was found to increase with increasing alkyl side chain length, and solubility of the homologous series decreases at higher rate than uptake increases. Uptake of higher homologue is not supposed to reach the level enough to inhibit growth of fungi, on account of its slight solubility.These results explain the reason why antifungal activity of p-n-alkylphenol increases with increasing alkyl chain length up to a certain homologue, and decreases for the higher members. 相似文献