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排序方式: 共有1396条查询结果,搜索用时 109 毫秒
1.
Iteng Ng-Choi ngel Oliveras Lidia Feliu Marta Planas 《International journal of peptide research and therapeutics》2020,26(2):695-707
The feasibility of the solid-phase intramolecular 4(5)-arylation of a histidine residue to obtain biaryl cyclic peptides bearing a His-Phe linkage was esta 相似文献
2.
V A Frolov G Mall P Rieger Kh Derks Z Antoni 《Biulleten' eksperimental'no? biologii i meditsiny》1987,104(12):739-741
Intensive synthesis of collagen-like substance was revealed in the rabbit myocardium during experimental diphtheria intoxication. It was more marked in the right ventricle 24 hours after the injection of diphtheria toxin. Since similar changes (the substance was mainly formed around blood vessels) have been observed in other cases of toxic myocardial alterations (i.e. ethanol intoxication, injection of pharmacological agents, etc.), it can be assumed that it is a standard protective reaction of the altered heart to the penetration of toxic agents from the blood into the myocardial tissue. 相似文献
3.
The five cysteines, at positions 82, 191, 192, 270, and 401, of Escherichia coli aspartate aminotransferase (AATase) were, individually and in some combinations, converted to alanine by site-directed mutagenesis (C82A, C191A, C192A, C270A, C401A). Cys-191, which is conserved in all AATase isozymes, was mutated to serine as well (C191S). A quintuple mutant, with all cysteines converted to alanines (Quint), was also constructed. The effects of these single and multiple mutations were examined by steady-state kinetics and urea denaturation. The thermal stabilities of Quint and of the wild-type enzyme (WT) were determined by differential scanning calorimetry. The mutants had kcat values up to 50% greater than that of WT and KMAsp and KM alpha-KG values up to 1.5- and 3.3-fold higher than that of WT. The mutants C82A and C191A exhibit nearly the same CM in urea denaturation experiments as WT, while the other single mutants and Quint are less stable, with CM differences of up to 0.7 M urea. Quint is also less thermostable than WT, with a delta TM of 3.3-4.4 degrees C. Thus the five cysteine replacements yield small, but significant, changes in catalytic and denaturation parameters, but none of the cysteines was found to be essential. The changes manifested in the mutation of the conserved Cys-191 to alanine are no greater than those observed with the four nonconserved cysteines. We consider the evolutionary implications of these findings. 相似文献
4.
F García J Sánchez J Planas 《Comparative biochemistry and physiology. A, Comparative physiology》1987,87(4):947-950
1. Male quails submitted 20 and 120 days to a low iron diet (7 ppm) were compared to female laying quails, exposed for 30 days to the same low iron regime, in order to compare the response of the iron metabolic control under a single (erythropoiesis) or a doubled (erythropoiesis and egg formation) iron demand. 2. Iron deposit in storage organs, the classical hematology and the intestinal iron absorption were analyzed in these animals. 3. In males, after 120 days, the iron deposits were reduced 50 and 75%, but hematological values (hematocrit and hemoglobin concentration) were normal, although in laying quails, after 30 days, an anemic condition was evident in both blood parameters and iron deposits, provoking an iron deficient erythropoiesis. 4. The enhancement of the intestinal iron uptake, confirms the anemic character of these birds. 相似文献
5.
Esteve Padrs Mireia Duach Antoni Morros Manuel Sabs Joan Maosa 《Trends in biochemical sciences》1984,9(12):508-510
Fourth-derivative spectrophotometry offers several advantages over classical absorption or difference spectrophotometry in examining the characteristics of aromatic amino acids in proteins. The basic principles of the technique and its applications are outlined. 相似文献
6.
7.
A Sóoki-Tóth G Bánfalvi J Sz?ll?si E Kirsten M Staub F Antoni E Kun 《Experimental cell research》1989,184(1):44-52
Thymic cells were isolated at intervals of between 0 and 144 h from mice that received one intraperitoneal injection of emetine (33 mg/kg), and thymus weight, incorporation of [14C]leucine into proteins and [3H]thymidine into DNA in intact thymic cells, as well as initial rates of protein ADP-ribosylation in permeabilized cells [A. Sóoki-Tóth, F. Asghari, E. Kirsten, and E. Kun (1987) Exp. Cell Res. 170, 93] were simultaneously monitored. The effect of emetine as an inhibitor of protein synthesis [F. Antoni, N. G. Luat, I. Csuka, I. Oláh, A. Sóoki-Tóth, and G. Bánfalvi (1987) Int. J. Immunopharmacol. 9, 333] corresponds to the induction of sequential cellular events, such as cell exit and remigration, by other antimitotic agents [C. Penit and F. Vasseur (1988) J. Immunol. 140, 3315] and produces an activation of proliferation of cells reentering into this organ. Proliferation, as demonstrated by a large increase in DNA synthesis and entrance into S phase, was kinetically related to an apparent increase in poly(ADP-ribose) polymerase activity in thymic cells and a highly significant in vitro ADP-ribosylation of histone H3. Since no DNA fragmentation occurred in thymic cells, as tested by a fluorometric technique [C. Birnboim and J. J. Jevac (1981) Cancer Res. 41, 1889], it is probable that a selective activation of poly(ADP-ribose) polymerase may have been induced in cells that undergo differentiation and proliferation while repopulating the thymus. 相似文献
8.
9.
Wojciech Uracz Jerzy Stachura Anna Pituch-Noworolska Tadeusz Popiela Antoni Czupryna Marek Zembala 《Cancer immunology, immunotherapy : CII》1988,27(2):171-176
Summary The expression of MHC class II determinants Ia.7 (detected by cross reactive mouse anti-Iak antibody) and HLA-DR on monocytes (MO) of gastric and colorectal cancer patients was examined. An increased proportion of MO bearing the Ia.7 determinant was found, while the number of MO expressing DR was not elevated. In gastric cancer patients the increased expression of the Ia.7 determinant was most pronounced in advanced cancer (stage IVA and IVB). The increased expression of this determinant was related to the presence of the tumour as the number of MO expressing Ia.7 decreased 6 months following surgical resection of the tumour. Further, the increased expression of Ia.7 on MO correlated with the tumour infiltration of the serosa. The Ia.7 determinants were mainly expressed on MO which also expressed the receptor for the Fc part of immunoglobulin. Immunostaining in cellular infiltrates surrounding the tumour revealed that Ia.7+ macrophages (MØ) were more numerous than in normal gastric mucosa and severe chronic gastritis and were mostly present in close proximity to tumour cells, while DR+ MØ were mainly localized within the stromal tissue of the tumour and their number was not increased in cancer infiltrates. These observations indicate that the Ia.7+ subpopulation of MØ may be involved in the anti-tumour response of the host. 相似文献
10.
Monoclonal antibodies against pertussis toxin subunits 总被引:2,自引:0,他引:2
Massimo Bigio Roberta Rossi Daniele Nucci Maria Giuseppina Borri Guido Antoni Antonella Bartoloni Rino Rappuoli 《FEMS microbiology letters》1988,51(1):7-11
Abstract Twenty monoclonal antibodies (mAbs) reacting with cholera toxin (CT) of Vibrio cholerae strain 569B were characterized in cross-section and GM1 ganglioside inhibition assays. MAbs were characterized by reaction with CT and Escherichia coli heat-labile porcine strain (LTp ) and human strain (LTh) enterotoxins, and by GM1 ganglioside inhibition of mAb binding. Eight of 10 CT-A specific and 3 of 10 CT-B-specific mAbs cross-reacted with LTh and LTp. GM1 ganglioside inhibited reactions of the CT-B cross-reacting antibodies. Results showed that these epitodes common to the B subunit of CT and LT are located in or near the GM1 ganglioside binding region, and that the GM1 ganglioside-binding region of LT differs from that of CT. 相似文献