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791.
Shichao Ma Shilei Zhang Wenhu Duan Wei Wang 《Bioorganic & medicinal chemistry letters》2009,19(14):3909-3911
An enantioselective approach to (+)-(S)-[n]-gingerols (1a–c) has been developed. The requisite stereogenic centers of target molecules are facilely constructed by the proline-catalyzed cross-aldol reaction from readily available achiral starting materials. 相似文献
792.
793.
Xingfu Zha Qingyou Xia Jun Duan Chunyun Wang Ningjia He Zhonghuai Xiang 《Insect biochemistry and molecular biology》2009,39(5-6):315-321
In many organisms, dosage compensation is needed to equalize sex-chromosome gene expression in males and females. Several genes on silkworm Z chromosome were previously detected to show a higher expression level in males and lacked dosage compensation. Whether silkworm lacks global dosage compensation still remains poorly known. Here, we analyzed male:female (M:F) ratios of expression of chromosome-wide Z-linked genes in the silkworm using microarray data. The expression levels of genes on Z chromosome in each tissue were significantly higher in males compared to females, which indicates no global dosage compensation in silkworm. Interestingly, we also found some genes with no bias (M:F ratio: 0.8–1.2) on the Z chromosome. Comparison of male-biased (M:F ratio more than 1.5) and unbiased genes indicated that the two sets of the genes have functional differences. Analysis of gene expression by sex showed that M:F ratios were, to some extent, associated with their expression levels. These results provide useful clues to further understanding roles of dosage of Z chromosome and some Z-linked sexual differences in silkworms. 相似文献
794.
XinXing Wang XiaoHua Liu RuiRui Kong Rui Zhan XiaoMing Wang Xue Leng JingBo Gong Meng Duan LiQun Wang Lei Wu LingJia Qian 《Cell stress & chaperones》2009,14(6):639-648
NGFI-B/Nur77/TR3, originally identified as an immediate-early gene rapidly induced by serum and growth factors, is a member of the steroid hormone nuclear receptor superfamily with no identified endogenous ligand. NGFI-B induces apoptosis in a number of cell lineages exposed to proapoptotic stimuli by directly targeting the mitochondria, inducing cytochrome c release. The present study was designed to determine the role of NGFI-B in cardiomyocytes of restraint-stressed rats. The NGFI-B content was increased in mitochondria and reduced in plasma as apoptosis increased. Analysis showed that NGFI-B induces cardiomyocyte apoptosis in restraint-stressed rats by mediating mitochondrial energy metabolism disorder. Several novel mitochondrial proteins, which correlate with NGFI-B, were reported in cardiomyocyte apoptosis of restraint-stressed rats. Five proteins associated with NGFI-B participate directly in mitochondrial energy metabolism. Studies of mitochondrial respiratory efficiency and ATP synthase activity strongly support the findings. These results provide significant information for comprehensively understanding the cellular mechanism of cardiovascular diseases. 相似文献
795.
Hongjie Duan Jiake Chai Zhiyong Sheng Yongming Yao Huinan Yin Liming Liang Chuanan Shen Jing Lin 《Apoptosis : an international journal on programmed cell death》2009,14(1):52-65
The purpose of this study was to investigate the occurrence and possible mechanisms of apoptosis in skeletal muscles after
burn injury. After a 40% body surface area burn to rats, TA muscles were examined for apoptosis at varying times by TEM, TUNEL
and cell death ELISA assay. Thermal injury was found to induce apoptosis in skeletal muscle on the first day and maximal apoptosis
appeared 4 days post-injury. Apoptotic ligands in serum assessed by ELISA revealed rapidly increase of TNF-α and subsequent
increase of sFasL to sFas ratio after burn injury. It implied TNF-α induced apoptosis in early stage and FasL induced apoptosis
in later stage after burn injury. Apoptosis-related genes/proteins in skeletal muscles examined by real-time PCR array and
Western blotting showed pro-apoptotic genes/proteins, including Tnfrsf1a, Tnfrsf1b and Tnfsf6 in TNF ligand and receptor family,
Bax and Bid in Bcl-2 family, caspase-3 and caspase-6 in caspase family, Dapk1, FADD and Cidea in death and CIDE domain family,
Apaf-1 in CARD family, and Gadd45a were up-regulated, while anti-apoptotic gene Bnip1 was down-regulated compared with that
of time-matched controls. In addition, increment of caspase-3, caspase-8 and caspase-9 activity provided further evidence
for their role in apoptosis in skeletal muscle. Significant increase in expression in pro-apoptotic genes/proteins and activity
of caspases suggested that death receptor-mediated signaling pathways and other apoptotic related pathways participated in
apoptosis in skeletal muscle after burn injury. However, it was found that some anti-apoptotic genes such as Bcl2l1, Mcl-1,
Nol-3, Il-10 and Prok2 were also up-regulated, which might imply the co-existence of protective response of the body after
burns. In conclusion, the data suggest that apoptosis and pro-apoptotic signaling are enhanced in muscles of burned rats.
To further elucidate the underlying apoptotic mechanisms mediating the atrophic response is important in establishing potential
therapeutic interventions that could prevent and/or reduce skeletal muscle wasting and preserve its physiological function. 相似文献
796.
Ning Zhang Guangyou Duan Tao Zhang 《Biochemical and biophysical research communications》2009,386(3):537-76
It is widely considered that it is not appropriate to treat β-pairs in isolation, since other secondary structural models (such as helices, coils), protein topology and protein tertiary structures would limit β-strand pairing. However, to understand the underlying mechanisms of β-sheet formation, studies ought to be performed separately on more concrete aspects. In this study, we focus on the parallel or antiparallel orientation of β-strands. First, statistical analysis was performed on the relative frequencies of the interstrand amino acid pairs within parallel and antiparallel β-strands. Consequently, features were extracted by singular value decomposition from the statistical results. By using the support vector machine to distinguish the features extracted from the two types of β-strands, high accuracy was achieved (up to 99.4%). This suggests that the interstrand amino acid pairs play a significant role in determining the parallel or antiparallel orientation of β-strands. These results may provide useful information for developing other useful algorithms to examine to the β-strand folding pathways, and could eventually lead to protein structure predictions. 相似文献
797.
The recently determined crystal structure of the human β2-adrenergic (β2AR) G-protein-coupled receptor provides an excellent structural basis for exploring β2AR-ligand binding and dissociation process. Based on this crystal structure, we simulated ligand exit from the β2AR receptor by applying the random acceleration molecular dynamics (RAMD) simulation method. The simulation results showed that the extracellular opening on the receptor surface was the most frequently observed egress point (referred to as pathway A), and a few other pathways through interhelical clefts were also observed with significantly lower frequencies. In the egress trajectories along pathway A, the D192-K305 salt bridge between the extracellular loop 2 (ECL2) and the apex of the transmembrane helix 7 (TM7) was exclusively broken. The spatial occupancy maps of the ligand computed from the 100 RAMD simulation trajectories indicated that the receptor-ligand interactions that restrained the ligand in the binding pocket were the major resistance encountered by the ligand during exit and no second barrier was notable. We next performed RAMD simulations by using a putative ligand-free conformation of the receptor as input structure. This conformation was obtained in a standard molecular dynamics simulation in the absence of the ligand and it differed from the ligand-bound conformation in a hydrophobic patch bridging ECL2 and TM7 due to the rotation of F193 of ECL2. Results from the RAMD simulations with this putative ligand-free conformation suggest that the cleft formed by the hydrophobic bridge, TM2, TM3, and TM7 on the extracellular surface likely serves as a more specific ligand-entry site and the ECL2-TM7 hydrophobic junction can be partially interrupted upon the entry of ligand that pushes F193 to rotate, resulting in a conformation as observed in the ligand-bound crystal structure. These results may help in the design of β2AR-targeting drugs with improved efficacy, as well as in understanding the receptor subtype selectivity of ligand binding in the β family of the adrenergic receptors that share almost identical ligand-binding pockets, but show notable amino acid sequence divergence in the putative ligand-entry site, including ECL2 and the extracellular end of TM7. 相似文献
798.
Yi Jin Ling Duan Seon Hwa Lee Helenius J. Kloosterboer Ian A. Blair Trevor M. Penning 《The Journal of biological chemistry》2009,284(15):10013-10022
799.
800.