排序方式: 共有68条查询结果,搜索用时 15 毫秒
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Oriane Frances Fataneh Fatemi Denis Pompon Eric Guittet Christina Sizun Javier Pérez Ewen Lescop Gilles Truan 《Biophysical journal》2015,108(6):1527-1536
Diflavin reductases are bidomain electron transfer proteins in which structural reorientation is necessary to account for the various intramolecular and intermolecular electron transfer steps. Using small-angle x-ray scattering and nuclear magnetic resonance data, we describe the conformational free-energy landscape of the NADPH-cytochrome P450 reductase (CPR), a typical bidomain redox enzyme composed of two covalently-bound flavin domains, under various experimental conditions. The CPR enzyme exists in a salt- and pH-dependent rapid equilibrium between a previously described rigid, locked state and a newly characterized, highly flexible, unlocked state. We further establish that maximal electron flux through CPR is conditioned by adjustable stability of the locked-state domain interface under resting conditions. This is rationalized by a kinetic scheme coupling rapid conformational sampling and slow chemical reaction rates. Regulated domain interface stability associated with fast stochastic domain contacts during the catalytic cycle thus provides, to our knowledge, a new paradigm for improving our understanding of multidomain enzyme function. 相似文献
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Ismael Sánchez-Jiménez Jaume Pellicer Oriane Hidalgo Sònia Garcia Teresa Garnatje Joan Vallès 《Folia Geobotanica》2009,44(3):307-322
Chromosome counts are reported for 15 species of the family Asteraceae from Inner Mongolia (People’s Republic of China). This study includes representatives of the tribes Anthemideae (Artemisia, Chrysanthemum, Filifolium, Hippolytia and Neopallasia), Astereae (Heteropappus) and Cardueae (Echinops and Olgaea). The significance of the chromosome counts is discussed for each species. Within the Anthemideae, chromosome counts for Hippolytia alashanensis (2n?=?36) and the tetraploid level of Artemisia eriopoda (2n?=?36) are reported for the first time. The chromosome number of Heteropappus altaicus (Astereae) agrees with previous reports of one (4x) of the two ploidy levels reported for this taxon. As a complement to the karyological data, genome size of the Cardueae representatives was assessed using flow cytometry. Within this tribe, Echinops gmelini (2n?=?26) and its sister taxon E. acantholepis (2n?=?14) show strongly divergent karyological patterns of difficult interpretation, whereas the count of E. przewalskyi (2n?=?32), assigned here for the first time, coincides with those of its close relatives. In Olgaea tangutica, the chromosome count (2n?=?24) and genome size (2C?=?3.01 pg) given here are the first reports for both the species and the genus. 相似文献
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Perla Farhat Sonja Siljak‐Yakovlev Oriane Hidalgo Keith Rushforth Jim A. Bartel Nicolas Valentin Ilia J. Leitch Robert P. Adams 《植物分类学报:英文版》2022,60(4):824-834
While polyploidy (whole-genome multiplication) is generally considered rare in extant gymnosperms (with the exception of Ephedra, Ephedraceae), the occurrence of sporadic polyploid individuals belonging to various genera in the conifer family Cupressaceae has been reported in the literature. In addition, recent studies have revealed that polyploidy is not uncommon in the genus Juniperus (Cupressaceae), with tetraploid and hexaploid individuals reported in individuals collected from wild populations. Given these findings, we undertook a comprehensive screening of ploidy levels in 32 species belonging to the four genera that are phylogenetically closest to Juniperus (i.e.,Callitropsis, Hesperocyparis, Xanthocyparis, and Cupressus), referred to as the CaHXCu complex. In addition, we also determined the ploidy level of two accessions in the poorly studied tetraploid, Fitzroya cupressoides. Using flow cytometry together with published chromosome counts to assign ploidy levels, we show that all species of the CaHXCu complex are diploid except Xanthocyparis vietnamensis, which is tetraploid, with a genome size of 44.60 pg/2 C. This study opens up new opportunities for studying the impact and consequences of polyploidy on the evolution and adaptation of species in Cupressaceae. 相似文献