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排序方式: 共有141条查询结果,搜索用时 46 毫秒
1.
Walter Fahn Heidrun Gundlach Brigitte Deus-Neumann Joachim Stöckigt 《Plant cell reports》1985,4(6):333-336
From differentiated plants of Catharanthus roseus (L.) G. Don, a specific enzyme was isolated and named acetyl-CoA : 17-O-deacetylvindoline 17-O-acetyltransferase, acting on the biosynthetic formation of the Aspidosperma type alkaloid vindoline.The enzyme shows a high selectivity towards different substrates. The acetyl-CoA-dependent transferase also catalyses the reverse reaction by hydrolysis of the 17-O-acetyl group of vindoline in the presence of free CoA. This enzyme is localized only in vindoline-containing plant parts, but was so far not detectable in cell suspension cultures of C. roseus. The enzyme allows the synthesis of labelled vindoline with high specific activity, applicable for instance as tracer for radioimmunoassays of vindoline. 相似文献
2.
The expression and distribution of mRNA encoding preproatrial natriuretic peptide (ppANP) in rat brain has been investigated by in situ hybridization of two 35S-labeled synthetic DNA oligonucleotides, based on a cDNA clone sequence that encodes rat ppANP. The highest relative concentrations of ppANP mRNA were detected in the medial preoptic hypothalamic nucleus ("anteroventral/third ventricle region") and the medial habenula. Moderate concentrations of ppANP mRNA were observed in the CA1 pyramidal cells of the hippocampus, the endopiriform nucleus, the arcuate nucleus, the zona incerta, and cells of the pontine tegmental and peduculopontine nuclei. Several of these regions, including the habenula and the hypothalamic areas, have previously been reported to contain atrial natriuretic peptide (ANP)-like immunoreactivity, but the expression of ppANP mRNA in CA1 pyramidal cells suggests the occurrence of differential translation of ppANP mRNA into protein product in different brain regions, or the existence of different immunological forms of the peptide. The abundance of ppANP mRNA in brain was relatively low in comparison with that previously reported for many other mRNA species encoding other brain neuropeptides. These results demonstrate that ANP gene expression occurs in discrete neuronal populations of the CNS and that studies of the regulation of this expression should now be possible using quantitative in situ hybridization. 相似文献
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4.
Pinard R Lambert D Heckman JE Esteban JA Gundlach CW Hampel KJ Glick GD Walter NG Major F Burke JM 《Journal of molecular biology》2001,307(1):51-65
The two domains of the hairpin ribozyme-substrate complex, usually depicted as straight structural elements, must interact with one another in order to form an active conformation. Little is known about the internal geometry of the individual domains in an active docked complex. Using various crosslinking and structural approaches in conjunction with molecular modeling (constraint-satisfaction program MC-SYM), we have investigated the conformation of the substrate-binding domain in the context of the active docked ribozyme-substrate complex. The model generated by MC-SYM showed that the domain is not straight but adopts a bent conformation (D-shaped) in the docked state of the ribozyme, indicating that the two helices bounding the internal loop are closer than was previously assumed. This arrangement rationalizes the observed ability of hairpin ribozymes with a circularized substrate-binding strand to cleave a circular substrate, and provides essential information concerning the organization of the substrate in the active conformation. The internal geometry of the substrate-binding strand places G8 of the substrate-binding strand near the cleavage site, which has allowed us to predict the crucial role played by this nucleotide in the reaction chemistry. 相似文献
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This article is concerned with the characterization and existence of evolutionarily stable strategies (ESS) in Games against Nature, a class of models described by finite size populations and absolute fitness measures. We address these problems in terms of a new formalism which revolves around the concept evolutionary entropy, a measure of the diversity of options associated with a strategy pure - strategies have zero entropy, mixed strategies positive entropy. We invoke this formalism to show that ESS are characterized by extremal states of entropy. We illustrate this characterization of ESS by an analysis of the evolution of the sex ratio and the evolution of seed size. 相似文献
7.
Jan Gundlach Achim Dickmanns Kathrin Schr?der-Tittmann Piotr Neumann Jan Kaesler Jan Kampf Christina Herzberg Elke Hammer Frank Schwede Volkhard Kaever Kai Tittmann J?rg Stülke Ralf Ficner 《The Journal of biological chemistry》2015,290(5):3069-3080
The cyclic dimeric AMP nucleotide c-di-AMP is an essential second messenger in Bacillus subtilis. We have identified the protein DarA as one of the prominent c-di-AMP receptors in B. subtilis. Crystal structure analysis shows that DarA is highly homologous to PII signal transducer proteins. In contrast to PII proteins, the functionally important B- and T-loops are swapped with respect to their size. DarA is a homotrimer that binds three molecules of c-di-AMP, each in a pocket located between two subunits. We demonstrate that DarA is capable to bind c-di-AMP and with lower affinity cyclic GMP-AMP (3′3′-cGAMP) but not c-di-GMP or 2′3′-cGAMP. Consistently the crystal structure shows that within the ligand-binding pocket only one adenine is highly specifically recognized, whereas the pocket for the other adenine appears to be promiscuous. Comparison with a homologous ligand-free DarA structure reveals that c-di-AMP binding is accompanied by conformational changes of both the fold and the position of the B-loop in DarA. 相似文献
8.
9.
Ponnada Suresh Kumar KK Pulicherla Mrinmoy Ghosh Anmol Kumar KRS Sambasiva Rao 《Bioinformation》2011,6(8):311-314
Enzymes from psychrophiles catalyze the reactions at low temperatures with higher specific activity. Among all the psychrophilic enzymes produced, cold active
β-galactosidase from marine psychrophiles revalorizes a new arena in numerous areas at industrial level. The hydrolysis of lactose in to glucose and galactose by
cold active β-galactosidase offers a new promising approach in removal of lactose from milk to overcome the problem of lactose intolerance. Herein we propose, a
3D structure of cold active β-galactosidase enzyme sourced from Pseudoalteromonas haloplanktis by using Modeler 9v8 and best model was developed having
88% of favourable region in ramachandran plot. Modelling was followed by docking studies with the help of Auto dock 4.0 against the three substrates lactose,
ONPG and PNPG. In addition, comparative docking studies were also performed for the 3D model of psychrophilic β-galactosidase with mesophilic and
thermophilic enzymes. Docking studies revealed that binding affinity of enzyme towards the three different substrates is more for psychrophilic enzyme when
compared with mesophilic and thermophilic enzymes. It indicates that the enzyme has high specific activity at low temperature when compared with mesophilic
and thermophilic enzymes. 相似文献
10.
Mayer KF Martis M Hedley PE Simková H Liu H Morris JA Steuernagel B Taudien S Roessner S Gundlach H Kubaláková M Suchánková P Murat F Felder M Nussbaumer T Graner A Salse J Endo T Sakai H Tanaka T Itoh T Sato K Platzer M Matsumoto T Scholz U Dolezel J Waugh R Stein N 《The Plant cell》2011,23(4):1249-1263
We used a novel approach that incorporated chromosome sorting, next-generation sequencing, array hybridization, and systematic exploitation of conserved synteny with model grasses to assign ~86% of the estimated ~32,000 barley (Hordeum vulgare) genes to individual chromosome arms. Using a series of bioinformatically constructed genome zippers that integrate gene indices of rice (Oryza sativa), sorghum (Sorghum bicolor), and Brachypodium distachyon in a conserved synteny model, we were able to assemble 21,766 barley genes in a putative linear order. We show that the barley (H) genome displays a mosaic of structural similarity to hexaploid bread wheat (Triticum aestivum) A, B, and D subgenomes and that orthologous genes in different grasses exhibit signatures of positive selection in different lineages. We present an ordered, information-rich scaffold of the barley genome that provides a valuable and robust framework for the development of novel strategies in cereal breeding. 相似文献