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61.
The contribution of naturally occurring polymorphisms in altering the biochemical and structural characteristics of HIV-1 subtype C protease 总被引:1,自引:0,他引:1
Coman RM Robbins AH Fernandez MA Gilliland CT Sochet AA Goodenow MM McKenna R Dunn BM 《Biochemistry》2008,47(2):731-743
Fourteen subtype B and C protease variants have been engineered in an effort to study whether the preexistent baseline polymorphisms, by themselves or in combination with drug resistance mutations, differentially alter the biochemical and structural features of the subtype C protease when compared with those of subtype B protease. The kinetic studies performed in this work showed that the preexistent polymorphisms in subtype C protease, by themselves, do not provide for a greater level of resistance. Inhibition analysis with eight clinically used protease inhibitors revealed that the natural polymorphisms found in subtype C protease, in combination with drug resistance mutations, can influence enzymatic catalytic efficiency and inhibitor resistance. Structural analyses of the subtype C protease bound to nelfinavir and indinavir showed that these inhibitors form similar interactions with the residues in the active site of subtype B and C proteases. It also revealed that the naturally occurring polymorphisms could alter the position of the outer loops of the subtype C protease, especially the 60's loop. 相似文献
62.
P Viallet E Kohen D O Schachtschabel A Marty J M Salmon C Kohen H B Leising B Thorell 《Histochemistry》1978,57(3):189-201
Coenzyme fluorescence spectra of single living cells are due to free pyridine nucleotides (folded configuration), bound pyridine nucleotides (unfolded configuration) and a third component, possibly a mixture or flavins. Such spectra can be used to recognize possible differences in coenzyme composition between cell lines or changes of metabolic pathways due to chemicals acting at levels below or above cytotoxicity, by high resolution spectrofluorometry. A study of spectra recorded from cultured Ehrlich ascites (EL2), and Harding Passey melanoma cells (HPM-67 and HPM-73 line) grown under comparable conditions, shows that free NAD(P)H predominates in HPM-67 and EL2, while this coenzyme is bound in HPM-73. The free/bound ratio may be profoundly modifed by chemicals, e.g. in the HPM-73 increase of free and decrease of bound NAD(P)H occurred upon treatment with 10(-6) oligomycin. When atebrine at levels (10(-6) M) below cytotoxicity was added, there was a decrease of the free NAD(P)H spectrum possibly through energy transfer from NAD(P)H to atebrine. Consideration of long range energy transfer i.e., excitation of atebrine by fluorescence of NAD(P)H vs. short range transfer of excitation energy from free NAD(P)H to atebrine, favors the latter mechanism. A transient (reversible) increase in atebrine fluorescence is seen following intracellular microinjection of substrate (e.g. glucose-6-P) leading to an increase in free NAD(P)H. At cytotoxic levels of atebrine (e.g 2 x 10(-5) M) an irreversible increase of atebrine fluorescence is seen. The microspectrofluorometric technique appears therefore well suited to study physiological processes at the level of intracellular coenzymes, as well as possible processes of intermolecular energy transfer in the microenvironment. 相似文献
63.
64.
Marty Shankland 《BioEssays : news and reviews in molecular, cellular and developmental biology》1994,16(11):801-808
A variety of leech homeobox genes have been identified by homology with genes that are known to bring about the regionalization and segmentation of the anteroposterior body axis in other organisms. Embryonic expression patterns suggest a number of interphyletic similarities in the way that these genes are utilized. However, several interesting differences have also been observed. In particular, transplantation experiments in the leech embryo have shown that axially aligned patterns of homeobox gene expression are not specified by a global pattern of positional cues. Rather, the leech independently establishes anteroposterior patterns of gene expression in each of five discrete stem cell lineages, and these patterns are brought into their final alignment through a process of morphogenetic assembly. 相似文献
65.
Improved Screening of cDNAs Generated by mRNA Differential Display Enables the Selection of True Positives and the Isolation of Weakly Expressed Messages 总被引:22,自引:1,他引:21
Zegzouti Hicham Marty Christel Jones Brian Bouquin Thomas Latché Alain Pech Jean Claude Bouzayen Mondher 《Plant Molecular Biology Reporter》1997,15(3):236-245
The high percentage of false positives generated by differential display (as high as 85%) has previously limited the potential of the method. This report describes an efficient methodology that enables false positives to be discarded prior to cloning, via reverse Northern analysis. This first step of the screening also allows the detection of putative low abundance differential clones. Following cloning, a second reverse Northern combined with partial DNA sequencing and RT-PCR detection allows isolation of all differential cDNAs including very low abundance clones. Use of the sequential screening procedure described here led to the isolation of novel tomato genes responding to the plant hormone ethylene while minimising labor and materials input. 相似文献
66.
The performance of a crude extract lipase from Pseudomonas fluorescensin esterification was evaluated in microaqueous, biphasic and surfactant-enriched biphasic systems containing various amounts of water (from almost no water to pure water). The results showed a strong negative influence of the water content on the thermodynamic equilibrium of the reaction in biphasic systems. From a kinetic point of view, the enzyme was more efficient in systems involving a water/organic solvent interface (4 times in the biphasic system, 12 times in the surfactant-enriched biphasic system). 相似文献
67.
Sylvie Baltora-Rosset Danielle Marty François-Yves Dupradeau Emmanuel Pauthe Véronique Larreta-Garde Gilles Gacel Jean-Pierre Monti 《International journal of peptide research and therapeutics》1997,4(4-6):391-395
Summary The conformations of thermolysin synthetic substrates in H2O/D2O (9/1) and glycerol-d
5 (5 M) are investigated using two-dimensional nuclear magnetic resonance spectroscopy and molecular modeling. The structures
obtained from molecular modeling and NMR studies are compared. Comparisons of these structures with bound inhibitor in the
active site of thermolysin are also discussed. 相似文献
68.
69.
Desiccation and osmotic stress increase the abundance of mRNA of the tonoplast aquaporin BobTIP26-1 in cauliflower cells 总被引:8,自引:0,他引:8
François Barrieu Danièle Marty-Mazars Dominique Thomas François Chaumont Maryse Charbonnier Francis Marty 《Planta》1999,209(1):77-86
Changes in vacuolar structure and the expression at the RNA level of a tonoplast aquaporin (BobTIP26-1) were examined in
cauliflower (Brassicaoleracea L. var. botrytis) under water-stress conditions. Gradual drying out of slices of cauliflower floret tissue caused its collapse, with a shrinkage
in tissue and cell volumes and an apparent vesiculation of the central vacuole, whereas osmotic stress resulted in plasmolysis
with a collapse of the cytoplasm and the central vacuole within. Osmotic stress caused a rapid and substantial increase in
BobTIP26 mRNA in slices of floret tissue. Exposure of tissue slices to a regime of desiccation showed a slower but equally large rise
in BobTIP26 mRNA followed by a rapid decline upon rehydration. In situ hybridization showed that BobTIP26-2 mRNA is expressed most highly in meristematic and expanding cells of the cauliflower florets and that desiccation strongly
increased the expression in those cells and in differentiated cells near the xylem vessels. These data indicate that under
water-deficit conditions, expression of the tonoplast aquaporin gene in cauliflower is subject to a precise regulation that
can be correlated with important cytological changes in the cells.
Received: 21 October 1998 / Accepted: 10 February 1999 相似文献
70.