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1.
The molybdenum cofactor is part of the active site of all molybdenum-dependent enzymes, except nitrogenase. The molybdenum cofactor consists of molybdopterin, a phosphorylated pyranopterin, with an ene-dithiolate coordinating molybdenum. The same pyranopterin-based cofactor is involved in metal coordination of the homologous tungsten-containing enzymes found in archea. The molybdenum cofactor is synthesized by a highly conserved biosynthetic pathway. In plants, the multidomain protein Cnx1 catalyses the insertion of molybdenum into molybdopterin. The Cnx1 G domain (Cnx1G), whose crystal structure has been determined in its apo form, binds molybdopterin with high affinity and participates in the catalysis of molybdenum insertion. Here we present two high-resolution crystal structures of Cnx1G in complex with molybdopterin and with adenylated molybdopterin (molybdopterin-AMP), a mechanistically important intermediate. Molybdopterin-AMP is the reaction product of Cnx1G and is subsequently processed in a magnesium-dependent reaction by the amino-terminal E domain of Cnx1 to yield active molybdenum cofactor. The unexpected identification of copper bound to the molybdopterin dithiolate sulphurs in both structures, coupled with the observed copper inhibition of Cnx1G activity, provides a molecular link between molybdenum and copper metabolism. 相似文献
2.
1Introduction Since 1980’s ,C1chemistryhashadrapiddevelopmentbasedoncarbonmonoxideascarbonsource .Itispossibletosynthetizemethylformate,dimethylether,ethanoicacid ,methanol,methylcarbonatefromCO[1-2 ] .Yellowphosphorustailgases,withtheirhighCOcontent,couldactasanattractiverawmaterialgasforsynthetizationoftheseandotherproducts.Thereare ,therefore,twobenefits,theavoidanceofenvironmentalpollutionandreductionincostsofyellowphosphorusproduction .However,existingtechniqueshavesomedisadvantages,… 相似文献
3.
Hans-J?rg Schek Heiko Schuldt Christoph Schuler Roger Weber 《Cellular and molecular life sciences : CMLS》1991,47(7):643-643
Science Policy News
United Kingdom: The Science and Engineering Research Council (SERC): A Report on Research in the United Kingdom, France and Germany (W) 相似文献4.
青藏高原是世界上面积最大、海拔最高的高原,其独特的地形地貌特征对东亚乃至全球大气环流有重要影响.由于地表特征不同,高原不同区域地表热力特征也有显著差异.高原的东部边缘地表、植被和气象特征与高原其他区域明显不同,因此这一区域地表热力作用也与高原其他区域不同.本文研究了青藏高原东部玛曲草原地表能量交换的季节变化特征.玛曲草原冬季净辐射占入射太阳辐射的比例小于雨季,其差异主要由2个季节的地表反照率和湿度状况的差异引起.全年来看,净辐射大部分用水汽蒸发所需的热量.冬季由于土壤冻结加之降水稀少,净辐射主要用于加热地表和大气.雨季由于相对较高的气温、充足的降水及植被茂盛的生长力,净辐射主要用于水汽蒸发.在这一区域,降水的季节分布以及土壤的冻融状况对地表能量分配有重要影响. 相似文献
5.
Witt H Sahin-Tóth M Landt O Chen JM Kähne T Drenth JP Kukor Z Szepessy E Halangk W Dahm S Rohde K Schulz HU Le Maréchal C Akar N Ammann RW Truninger K Bargetzi M Bhatia E Castellani C Cavestro GM Cerny M Destro-Bisol G Spedini G Eiberg H Jansen JB Koudova M Rausova E Macek M Malats N Real FX Menzel HJ Moral P Galavotti R Pignatti PF Rickards O Spicak J Zarnescu NO Böck W Gress TM Friess H Ockenga J Schmidt H Pfützer R Löhr M Simon P Weiss FU Lerch MM Teich N Keim V Berg T Wiedenmann B Luck W 《Nature genetics》2006,38(6):668-673
Chronic pancreatitis is a common inflammatory disease of the pancreas. Mutations in the genes encoding cationic trypsinogen (PRSS1) and the pancreatic secretory trypsin inhibitor (SPINK1) are associated with chronic pancreatitis. Because increased proteolytic activity owing to mutated PRSS1 enhances the risk for chronic pancreatitis, mutations in the gene encoding anionic trypsinogen (PRSS2) may also predispose to disease. Here we analyzed PRSS2 in individuals with chronic pancreatitis and controls and found, to our surprise, that a variant of codon 191 (G191R) is overrepresented in control subjects: G191R was present in 220/6,459 (3.4%) controls but in only 32/2,466 (1.3%) affected individuals (odds ratio 0.37; P = 1.1 x 10(-8)). Upon activation by enterokinase or trypsin, purified recombinant G191R protein showed a complete loss of trypsin activity owing to the introduction of a new tryptic cleavage site that renders the enzyme hypersensitive to autocatalytic proteolysis. In conclusion, the G191R variant of PRSS2 mitigates intrapancreatic trypsin activity and thereby protects against chronic pancreatitis. 相似文献
6.
Aiertza MK Odriozola I Cabañero G Grande HJ Loinaz I 《Cellular and molecular life sciences : CMLS》2012,69(3):337-346
The synthesis of polymer nanoparticles (NPs) with controlled characteristics has become an appealing research topic lately.
Nanomedicine, and especially drug delivery and imaging, are fields that require particles of a controlled size and with a
tailored arrangement of functional groups. Intramolecular cross-linking or collapse of single polymer chains has emerged as
an efficient alternative for the synthesis of well-defined polymer NPs. This technique allows the generation of 1.5–20 nm
particles with a wide variety of chemical compositions and functionalities. This review begins by gathering synthetic strategies
described in the literature and groups them into four main synthetic methods: homo-functional collapse, hetero-functional
collapse, crosslinker-mediated collapse, and one-block collapse of diblock or triblock copolymers. Afterwards, the main characterization
techniques and physical properties of single-chain polymer NPs (SCPNs) are exposed. Finally, several applications in nanomedicine
are mentioned followed by some future perspectives. 相似文献
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8.
Collective efforts are a trademark of both insect and human societies. They are achieved through relatedness in the former and unknown mechanisms in the latter. The problem of achieving cooperation among non-kin has been described as the 'tragedy of the commons', prophesying the inescapable collapse of many human enterprises. In public goods experiments, initial cooperation usually drops quickly to almost zero. It can be maintained by the opportunity to punish defectors or the need to maintain good reputation. Both schemes require that defectors are identified. Theorists propose that a simple but effective mechanism operates under full anonymity. With optional participation in the public goods game, 'loners' (players who do not join the group), defectors and cooperators will coexist through rock-paper-scissors dynamics. Here we show experimentally that volunteering generates these dynamics in public goods games and that manipulating initial conditions can produce each predicted direction. If, by manipulating displayed decisions, it is pretended that defectors have the highest frequency, loners soon become most frequent, as do cooperators after loners and defectors after cooperators. On average, cooperation is perpetuated at a substantial level. 相似文献
9.
Generation of pluripotent stem cells from adult human testis 总被引:2,自引:0,他引:2
Conrad S Renninger M Hennenlotter J Wiesner T Just L Bonin M Aicher W Bühring HJ Mattheus U Mack A Wagner HJ Minger S Matzkies M Reppel M Hescheler J Sievert KD Stenzl A Skutella T 《Nature》2008,456(7220):344-349
Human primordial germ cells and mouse neonatal and adult germline stem cells are pluripotent and show similar properties to embryonic stem cells. Here we report the successful establishment of human adult germline stem cells derived from spermatogonial cells of adult human testis. Cellular and molecular characterization of these cells revealed many similarities to human embryonic stem cells, and the germline stem cells produced teratomas after transplantation into immunodeficient mice. The human adult germline stem cells differentiated into various types of somatic cells of all three germ layers when grown under conditions used to induce the differentiation of human embryonic stem cells. We conclude that the generation of human adult germline stem cells from testicular biopsies may provide simple and non-controversial access to individual cell-based therapy without the ethical and immunological problems associated with human embryonic stem cells. 相似文献
10.
O'Donovan MC Craddock N Norton N Williams H Peirce T Moskvina V Nikolov I Hamshere M Carroll L Georgieva L Dwyer S Holmans P Marchini JL Spencer CC Howie B Leung HT Hartmann AM Möller HJ Morris DW Shi Y Feng G Hoffmann P Propping P Vasilescu C Maier W Rietschel M Zammit S Schumacher J Quinn EM Schulze TG Williams NM Giegling I Iwata N Ikeda M Darvasi A Shifman S He L Duan J Sanders AR Levinson DF Gejman PV Cichon S Nöthen MM Gill M Corvin A Rujescu D Kirov G Owen MJ Buccola NG Mowry BJ 《Nature genetics》2008,40(9):1053-1055
We carried out a genome-wide association study of schizophrenia (479 cases, 2,937 controls) and tested loci with P < 10(-5) in up to 16,726 additional subjects. Of 12 loci followed up, 3 had strong independent support (P < 5 x 10(-4)), and the overall pattern of replication was unlikely to occur by chance (P = 9 x 10(-8)). Meta-analysis provided strongest evidence for association around ZNF804A (P = 1.61 x 10(-7)) and this strengthened when the affected phenotype included bipolar disorder (P = 9.96 x 10(-9)). 相似文献