排序方式: 共有76条查询结果,搜索用时 15 毫秒
51.
Giannini G Marzi M Cabri W Marastoni E Battistuzzi G Vesci L Pisano C Beretta GL De Cesare M Zunino F 《Bioorganic & medicinal chemistry letters》2008,18(9):2910-2915
In contrast to five-membered E-ring analogues, 7-oxyiminomethyl derivatives of homocamptothecins showed ability to form stable ternary complexes with DNA and topoisomerase I. The 7-oxyiminomethyl derivatives of homocamptothecins were evaluated as a racemic mixture. Following the isolation of the two enantiomers, the 20 (R)-hydroxy isomer confirms the best activity. By using a panel of human tumor cells, all tested homocamptothecins showed a potent antiproliferative activity, correlating to the persistence of the cleavable complex. No significant difference was observed between the natural scaffold and the corresponding homocamptothecin homologue. A selected compound of this series exhibited an excellent antitumor activity against human gastrointestinal tumor xenografts. 相似文献
52.
Gianantonio Battistuzzi Maria Cannio Monica Saladini Raffaele Battistuzzi 《Inorganica chimica acta》2001,320(1-2):178-183
Reaction of 4,6-dimethylpyrimidine-2(1H)-thione (Me2pymSH) with mer-[ReOCl3(Me2S)(OPPh3)] synthon in 1:1 molar ratio in refluxing acetone, results in the replacement of the Me2S ligand to form the mer-[ReOCl3(Me2pymSH)(OPPh3)] species. X-ray diffraction shows that the structure of the title compound consists of monomeric units with a distorted octahedral coordination around the rhenium(V) centre which includes the axial ReO and Re---OPPh3 bonds, and in which three Cl− ions and a S-monodentate neutral Me2pymSH ligand act as equatorial ligands. The compound was also characterised using electrochemical measurements and UV–Vis–NIR and IR spectroscopy. 相似文献
53.
54.
Fabia?U?Battistuzzi Andreia?Feijao S?Blair?HedgesEmail author 《BMC evolutionary biology》2004,4(1):44
Background
The timescale of prokaryote evolution has been difficult to reconstruct because of a limited fossil record and complexities associated with molecular clocks and deep divergences. However, the relatively large number of genome sequences currently available has provided a better opportunity to control for potential biases such as horizontal gene transfer and rate differences among lineages. We assembled a data set of sequences from 32 proteins (~7600 amino acids) common to 72 species and estimated phylogenetic relationships and divergence times with a local clock method. 相似文献55.
The 1H NMR spectra of the fully oxidized Rhus vernicifera laccase and of its 1:1 and 2:1 azide adducts are reported for the first time. These spectra, which are the first so far reported for a multi copper oxidase, contain a number of broad hyperfine-shifted resonances in the high frequency region of the spectrum, which are attributed to the metal binding residues of the mononuclear T1 center. The differences between the patterns of the hyperfine resonances of the free enzyme and its azide derivatives suggest that the alterations in the structural properties of the T3 site induced by the binding of the first azide molecule induce a limited alteration of the spin density distribution over the T1 copper ligands. Overall, these data demonstrate that 1H NMR can be fruitfully applied to characterize the electronic properties of the metal sites of blue oxidases at room temperature. 相似文献
56.
Genetic heterogeneity at the glucose-6-phosphate dehydrogenase locus in southern Italy: a study on the population of Naples 总被引:3,自引:0,他引:3
Colonna-Romano S. Iolascon A. Lippo S. Pinto L. Cutillo S. Battistuzzi G. 《Human genetics》1985,69(3):228-232
Summary Glucose-6-phosphate dehydrogenase (G6PD) electrophoretic phenotype was determined in red cells from 979 male subjects born in Naples (Southern Italy). In 0.7% of the cases no activity could be detected in haemolysates, while in 1.3% of the cases G6PD activity was approximately 20% of normal and electrophoretic mobility was altered. Moveover in two subjects a G6PD with altered mobility and normal activity was shown. G6PD was characterized in 10 subjects with variant phenotype. We conclude that the G6PD(-) phenotype in the population of Naples consists of at least six different G6PD variants associated with mild deficiency and at least one, G6PD Mediterranean, associated with severe deficiency. 相似文献
57.
58.
Goldstein LH Dolinsky G Greenberg R Schaefer C Cohen-Kerem R Diav-Citrin O Malm H Reuvers-Lodewijks ME Rost van Tonningen-van Driel MM Arnon J Ornoy A Clementi M Di Gianantonio E Koren G Braunstein R Berkovitch M 《Birth defects research. Part A, Clinical and molecular teratology》2007,79(10):696-701
BACKGROUND: Azathioprine (AZP) interferes with nucleic acid synthesis and is teratogenic in animals. In view of the paucity of information on the use of AZP during pregnancy we investigated this subject in a prospective, controlled, multicenter study. Our objective was too determine whether exposure to AZP during pregnancy increases the risk for major malformations and to determine the effect on pregnancy outcome. METHODS: Pregnant women on AZP who contacted one of seven teratogen information services were compared to a cohort of pregnant women who contacted two of the seven teratogen information services and took nonteratogenic treatments during their pregnancy. RESULTS: Follow-up was completed on 189 women in the AZP group and compared to 230 women in the control group. The rate of major malformations did not differ between groups with six neonates in each; the AZP rate was 3.5% and the control group rate was 3.0% (p = .775; OR 1.17; CI: 0.37, 3.69). The mean birth weight and gestational age were lower in the AZP group (2,995 g vs. 3,252 g [p = .001, difference of mean: 257, 95% CI: 106.3, 408.1] and 37.8 weeks vs. 39.1 weeks [p = .001, difference of mean: 1.3, 95% CI: .5, 2.0], respectively). The AZP group had more cases of prematurity (21.4% vs. 5.2% [p < .001; OR 4.0; 95% CI: 2.0, 8.06]) and low birth weight (23% vs. 6.0% [p < .001; OR 3.81; 95% CI: 2.0, 7.2]). CONCLUSIONS: These results suggest that AZP (50-100 mg/day) does not triple the rate of birth defects; however, it is associated with lower birth weight, gestational age, and prematurity. Larger studies are needed to confirm these observations. 相似文献
59.
Gianantonio Battistuzzi Lodovica Loschi Marco Borsari M. Sola 《Journal of biological inorganic chemistry》1999,4(5):601-607
The effects of the ionic atmosphere on the enthalpic and entropic contributions to the reduction potential of native (state
III) beef heart cytochrome c have been determined through variable-temperature direct electrochemistry experiments. At neutral or slightly alkaline pH
values, from 5 to 50 °C, the reduction enthalpy and entropy become less negative with decreasing ionic strength. The reduction
entropy extrapolated at null ionic strength is approximately zero, indicating that, in the absence of the screening effects
of the salt ions on the network of the electrostatic interactions at the protein-solvent interface, the solvation properties
and the conformational flexibility of the two redox states are comparable. The moderate decrease in E°′ observed with increasing ionic strength [ΔE°′IS =(E°′)
I
=0.1 M–(E°′)
I
=0 M=–0.035 V at 25 °C], once the compensating enthalpic and entropic effects of the salt-induced changes in the hydrogen bonding
within the hydration sphere of the molecule in the two redox states are factorized out, results in being ultimately determined
by the stabilizing enthalpic effect of the negatively charged ionic atmosphere on the ferri form. At pH 9, the ionic strength
dependence of the reduction termodynamics of cytochrome c follows distinctive patterns, possibly as a result of specific binding of the hydroxide ion to the protein. A decrease in
ionic strength at constant pH, as well as a pH increase at constant ionic strength, induces a depression of the temperature
of the transition from the low-T to high-T conformer of cytochrome c, which suggests that a temperature-induced decrease in the pK
a for a residue deprotonation is the key event of this conformational change.
Received: 7 April 1999 / Accepted: 19 July 1999 相似文献
60.
Gianantonio Battistuzzi Marzia Bellei Carlo Augusto Bortolotti Marco Sola 《Archives of biochemistry and biophysics》2010,500(1):21-16961
Peroxidases are heme enzymes found in bacteria, fungi, plants and animals, which exploit the reduction of hydrogen peroxide to catalyze a number of oxidative reactions, involving a wide variety of organic and inorganic substrates. The catalytic cycle of heme peroxidases is based on three consecutive redox steps, involving two high-valent intermediates (Compound I and Compound II), which perform the oxidation of the substrates. Therefore, the thermodynamics and the kinetics of the catalytic cycle are influenced by the reduction potentials of three redox couples, namely Compound I/Fe3+, Compound I/Compound II and Compound II/Fe3+. In particular, the oxidative power of heme peroxidases is controlled by the (high) reduction potential of the latter two couples. Moreover, the rapid H2O2-mediated two-electron oxidation of peroxidases to Compound I requires a stable ferric state in physiological conditions, which depends on the reduction potential of the Fe3+/Fe2+ couple. The understanding of the molecular determinants of the reduction potentials of the above redox couples is crucial for the comprehension of the molecular determinants of the catalytic properties of heme peroxidases.This review provides an overview of the data available on the redox properties of Fe3+/Fe2+, Compound I/Fe3+, Compound I/Compound II and Compound II/Fe3+ couples in native and mutated heme peroxidases. The influence of the electron donor properties of the axial histidine and of the polarity of the heme environment is analyzed and the correlation between the redox properties of the heme group with the catalytic activity of this important class of metallo-enzymes is discussed. 相似文献