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101.
Gerrit J. Poelarends Hector Serrano Jamison P. Huddleston William H. Johnson Jr.Christian P. Whitman 《FEBS letters》2013
trans-3-Chloroacrylic acid dehalogenase (CaaD) catalyzes the hydrolytic dehalogenation of trans-3-haloacrylates to yield malonate semialdehyde by a mechanism utilizing βPro-1, αArg-8, αArg-11, and αGlu-52. These residues are implicated in a promiscuous hydratase activity where 2-oxo-3-pentynoate is processed to acetopyruvate. The roles of three nearby residues (βAsn-39, αPhe-39, and αPhe-50) are unexplored. Mutants were constructed at these positions (βN39A, αF39A, αF39T, αF50A and αF50Y) and kinetic parameters determined along with those of the αR8K and αR11K mutants. Analysis indicates that αArg-8, αArg-11, and βAsn-39 are critical for dehalogenase activity whereas αArg-11 and αPhe-50 are critical for hydratase activity. Docking studies suggest structural bases for these observations. 相似文献
102.
Matthias Burger 《Acta zoologica》2013,94(3):280-290
Spider genital morphology usually provides the best characters for taxonomy. Furthermore, functional genital morphology helps to understand the evolution of complex genitalia and their role in the context of sexual selection. The genital systems of most haplogyne spider families are poorly investigated with respect to their morphology. The present study investigates the female genitalia of the oonopids Oonops pulcher, Oonopinus kilikus, and Pseudotriaeris sp. by means of light microscopy and SEM. The male palps are briefly described. Females of O. pulcher store spermatozoa in an anterior and a posterior receptaculum (PRe). The genitalia resemble the primitive dysderoid genitalia supporting the hypothesis that the subfamily Oonopinae contains more basal oonopids. In O. kilikus, the anterior receptaculum is reduced to a sclerite. Spermatozoa are stored in a PRe. The receptacula of Pseudotriaeris sp. are reduced to sclerites. Spermatozoa in the uterus internus indicate that fertilization happens there or in the ovary. The anterior sclerite might serve females to lock the uterus during copulation as suggested for other gamasomorphines. The male palp of O. kilikus is simple, whereas the palps of O. pulcher and Pseudotriaeris sp. appear more complex. Complicated structures on the palp of Pseudotriaeris sp. indicate that males exert copulatory courtship. 相似文献
103.
104.
ZhiLi Fang WenCui Su WeiGuang Zhang Yan Xu YaJin Xiong MiaoLi Luo Jun Fan Xia Yin 《Journal of molecular recognition : JMR》2013,26(4):161-164
The chiral discrimination studies of biological system are theoretically and practically significant for the development of chiral drugs and life science. Our work has embarked upon the interaction between serum albumin (SA) (including human SA and bovine SA), R,S‐1‐(4‐methoxyphenyl)ethylamine, and R,S‐1‐(3‐methoxyphenyl)ethylamine. The formation of intermediate transition state, binding sites, and chiral discrimination ability can be investigated by ultraviolet‐visible spectra and fluorescence spectra. Moreover, both the changes of hydrophobic microenvironment and energy transfer can be detected by synchronous fluorescence spectra and fluorescence lifetime. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
105.
Akira Hasegawa Koji Kigawa Makoto Kiso Ichiro Azuma 《Bioscience, biotechnology, and biochemistry》2013,77(8):2091-2094
A variety of 1-O-acyl and 1,6-di-O-acyl derivatives of N-acetylmuramoyl-l-alanyl-G-isoglutamine methyl esters were synthesized from N-[2-O-(2-acetamido-2,3-dideoxy-4,6-O-iso- propylidene-d-glucopyranose-3-yl)-d-lactoyl]-l-alanyl-d-isoglutamine methyl ester, and their biological activities were examined in guinea-pigs and mice. 相似文献
106.
107.
Interferon regulatory factor-4 binding protein (IBP) is a novel upstream activator of Rho GTPases. Our previous studies have shown that ectopic expression of IBP was correlated with malignant behaviors of human breast cancer cells, and invasive human breast cancer had high expression of IBP that promoted the proliferation of these cells. However, it remains unknown whether autophagy inhibition contributes to IBP-mediated tumorigenesis. In this study, we for the first time, reported that upregulation of IBP expression significantly suppressed the autophagy of breast cancer cells, and downregulation of IBP expression markedly induced autophagy of these cells. Further investigation revealed that IBP effectively counteracted autophagy by directly activating mammalian target of rapamycin complex 2 (mTORC2) and upregulating phosphorylation of Akt on ser473 and FOXO3a on Thr32. Moreover, IBP-mediated suppression of autophagy was dependent on mTORC2/Akt/FOXO3a signaling pathway. Finally, our results demonstrated that IBP-mediated breast cancer cell growth in vitro and in vivo was strongly correlated with suppression of mTORC2-dependent autophagy. These findings suggest that the anti-autophagic property of IBP has an important role in IBP-mediated tumorigenesis, and IBP may serve as an attractive target for treatment of breast cancer. 相似文献
108.
Titanium alloy is one of the best materials for biomedical applications due to its superior biocompatibility, outstanding corrosion resistance, and low elastic modulus. However, the friction and wear behaviors of titanium alloys were sensitive to the environment including lubrication. In order to clarify the wear mechanism of titanium alloy under different lubrications including deionized water, physiological saline and bovine serum, the friction and wear tests were performed between Ti6Al4V plates and Si3N4 ball on a universal multi-functional tester. The friction and the wear rate of titanium alloy were measured under dry friction and three different lubrication conditions. The worn surfaces were examined by scanning electron microscopy. The results revealed that under the dry friction, the wear resistance of titanium alloy was the worst since the wear mechanism was mainly the combination of abrasive wear and oxidation wear. It was also found that Ti6Al4V alloy had low friction coefficient and wear rate under three lubrication conditions, and its wear mechanism was adhesive wear. 相似文献
109.
Although landing behaviour in anurans differs significantly among species, a take-off behaviour seems to be largely conserved in the evolution of frogs and toads. The ancestral mode of landing is hypothesized to involve the body crash-landing on the substrate, after which the anuran cycles the limbs forward and then backward to their resting position. The part of the body that first contacts the substrate may vary among taxa. The limbs and pectoral girdle muscles as well as those of the caudopelvic region, involved with landing and take-off behaviours, are investigated. The existence of a relationship exists between myology and different take-off and landing behaviours is explored. The results suggest that most of the muscles involved in both take-off and landing are conserved morphologically, with only few differing, depending on the locomotor behaviour. Two muscles tend to be longer; the m. coracobrachialis, which is involved with landing, and the m. coccygeosacralis, related to the take-off. 相似文献
110.
Plant-derived antimicrobial agents have received increasing attention owing to their potential to control pathogens and excellent efficacy despite the growing prevalence of antibiotic resistance. However, the antibacterial mechanism of juglone, a traditional medicine used to cure skin infections, is still unclear. Therefore, in this study, in order to elucidate the mechanisms underlying the antibacterial activity of juglone, label-free quantitative proteomic technology was applied for analysis of the 417 proteins that were differentially expressed in Escherichia coli after treatment with juglone at one-half of the minimum inhibitory concentration. Gene ontology enrichment analysis of differentially expressed proteins suggested that juglone effectively repressed the expression of dehydrogenase and cytochrome oxidase, indicating that energy generation was blocked. Additionally, juglone induced RNA formation and ribosome assembly, resulting in inhibition of translation. This is the first study to adopt a proteomic approach to investigate the antibacterial mechanism of action of juglone against E. coli. 相似文献