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941.
Tabrez Shams Jabir Nasimudeen R. Zughaibi Torki A. Shakil Shazi 《Molecular biology reports》2021,48(10):6695-6702
Molecular Biology Reports - Complex coronary atherosclerotic lesions often lead to coronary occlusion, clinically represented as a single-vessel disease (SVD) and multivessel... 相似文献
942.
Activities of Escherichia coli DNA polymerase-I were examined in the presence of the anti-tumor drug cis-diaminedichloroplatinum(II) and its inactive geometric isomer trans-diaminedichloroplatinum(II). The trans-isomer did not inhibit the enzyme activity. The anti-tumor drug, on the other hand, retarded the enzyme in its ability to extend the primer strand of DNA. Two alternative mechanisms of inhibition, covalent binding of cis-diaminedichloroplatinum(II) to the polymerase and to the template DNA, were explored. Selective preincubations of the platinum drug with the polymerase and DNA reveal that the inhibition is primarily due to covalent binding to the enzyme. The rates of inhibition were found to be first order in enzyme and zeroth order in platinum in the concentration range 0.05-3.0 mM. A mechanism that deals with the formation of an initial platinum-polymerase-I complex with a binding constant > 10(5) M(-1) followed by a further reaction to form an inhibitory complex is consistent with the kinetic data. The rate limiting first order rate constant for the formation of the inhibitory complex is comparable to that observed for the thiol coordination of peptides containing cysteine residues. Analyses of known structures and functions of catalytic domains of various polymerases point to the direction that the inhibition is perhaps due to the distortion of the DNA binding domain of the enzyme due to platinum coordination. 相似文献
943.
D C Rideout M Lambert D A Kendall G R Moe D G Osterman H P Tao I B Weinstein E T Kaiser 《Journal of cellular physiology》1985,124(3):365-371
Four amphiphilic peptides, each with net charges of +2 or more at neutrality and molecular weights under 4 kilodaltons, were found to mediate the adhesion of normal rat kidney fibroblasts to polystyrene surfaces. Two of these peptides, a model for calcitonin (peptide 1, MCT) and melittin (peptide 2, MEL), form amphiphilic alpha-helical structures at aqueous/nonpolar interfaces. The other two, a luteinizing hormone-releasing hormone model (peptide 3, LHM) and a platelet factor model (peptide 4, MPF) form beta-strand structures in amphiphilic environments. Although it contains only 10 residues, LHM mediated adhesion to surfaces coated with solutions containing as little as 10 pmoles/ml of peptide. All four of these peptides were capable of forming monolayers at air-buffer interfaces with collapse pressures greater than 20 dynes/cm. None of these four peptides contains the tetrapeptide sequence Arg-Gly-Asp-Ser, which has been associated with fibronectin-mediated cell adhesion. Ten polypeptides that also lacked the sequence Arg-Gly-Asp-Ser but were nonamphiphilic and/or had net charges less than +2 at neutrality were all incapable of mediating cell adhesion (Pierschbacher and Ruoslahti, 1984). The morphologies of NRK cells spread on polystyrene coated with peptide LHM resemble the morphologies on fibronectin-coated surfaces, whereas cells spread on surfaces coated with MCT or MEL exhibit strikingly different morphologies. The adhesiveness of MCT, MEL, LHM, and MPF implies that many amphiphilic cationic peptides could prove useful as well defined adhesive substrata for cell culture and for studies of the mechanism of cell adhesion. 相似文献
944.
945.
R Sitia H Kikutani A Rubartelli Y Bushkin J Stavnezer U Hammerling 《Journal of immunology (Baltimore, Md. : 1950)》1982,128(2):712-716
Three different forms of alpha-chains are synthesized by BF0.3 and 615.2, two cloned cell lines derived from the murine B lymphoma 1.29. The three forms of alpha-chains differ in size, pI, cellular location, and rate of turnover. They were identified by means of lactoperoxidase-catalyzed radioiodination, internal 14C or 35S labeling, and immunofluorescence techniques as membrane-bound(alpha m), secreted (alpha s), and intracellular (alpha ic) proteins. Comparison of immunoglobulin products of the two lymphoma lines with those of a hybridoma cell line, Id 150, which secretes IgA of the 1.29 idiotype but lacks membrane IgA, confirmed the assignments of alpha m, alpha s, and alpha ic. Results of biosynthetic labeling of BF0.3, 615.2, and Id 150 in the presence and absence of tunicamycin suggest that the difference in m.w. and charge observed between alpha m and alpha s can be attributed to differences in primary amino acid structure rather than different degrees of glycosylation. 相似文献
946.
A total of 381 patients with established (156) or potential (225) sinoatrial dysfunction were included in a 10-year prospective survey to determine the course of the disease and the benefits of pacing. With the exclusion of nine patients who were lost to follow-up, 61 were fitted with pacemakers. The overall survival of patients with established and potential dysfunction was similar and apparently indistinguishable from that of the normal population. Pacemaker implantation had little discernible effect on mortality though it reduced some incapacitating symptoms. These findings suggest that sinoatrial dysfunction is a relatively benign condition. Hence pacing should probably not be adopted as a routing measure but be reserved for patients with troublesome symptoms. 相似文献
947.
Summary An improved method for separating analogues of coenzyme F420 by isocratic reversed-phase high performance liquid chromatography is described. The method offers improved resolution, shorter chromatography runs and requires less complex apparatus. 相似文献
948.
C D Wolleben R K McPherson J Rulfs G L Johnson T B Miller 《Biochimica et biophysica acta》1987,928(1):98-106
The phosphorylation of glycogen synthase has been studied in freshly isolated adult rat cardiomyocytes. Six peaks of 32P-labeled tryptic peptides are recovered via C-18 high performance liquid chromatography (HPLC) when synthase is immunoprecipitated from 32P-labeled cardiomyocytes and digested with trypsin. When epinephrine treated cells are used as a source of enzyme, the same HPLC profile is obtained with a dramatic enhancement of 32P recovered in two of the HPLC peaks. In vitro phosphorylation of rat heart synthase by cAMP-dependent protein kinase stimulates the conversion of synthase from the I to the D form and results in the recovery of the same tryptic peptides from the C-18 as is the case for synthase derived from cardiomyocytes. Treatment of cAMP-dependent kinase phosphorylated synthase with protein phosphatase-1 leads to a reactivation of the enzyme and a dephosphorylation of the same tryptic peptides that are selectively phosphorylated in epinephrine treated cardiomyocytes. These results are discussed in relation to hormonal control of glycogen metabolism in cardiac tissue. 相似文献
949.
950.
The present study has shown that on the level of the parasitic system the epidemic process is a biological system, wherein the host population serves as the internal regulator, the mechanism of transmission serves as the external regulator and the parasite population, as the regulated object. The biological regulating mechanisms of the epidemic process have fundamental differences in the groups of infectious with various mechanisms of transmission, and the specific nature of the mechanism of transmission determines the peculiar features of the biological mechanism which governs the self-regulation of the epidemic process. In contrast, on a higher level of the organization of the epidemic process, i. e. on the level of the socio-ecological system, the epidemic process is a biosocial system, wherein the human society serves as the regulator, the parasitic system serves as the regulated object and the mechanism of transmission plays the role of the filter which determines the scope of social factors, most important in the regulation of the epidemic process in a given infection. The spontaneous regulation of the epidemic process is the freed forward channel from the regulator to the regulated object, and the controlled regulation is the feedback channel. 相似文献