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Judith Barends Johannes B. van der Linden Floris L. Van Delft Gerrit-Jan Koomen 《Nucleosides, nucleotides & nucleic acids》2013,32(9):2121-2126
Abstract Room-temperature treatment of persilylated 6-chloro-9-β-D-ribofuranosyl-purine with a variety of aliphatic and aromatic amines, in the presence of Pd2(dba)3, BINAP and base, leads to N6-substituted adenosine analogues in fair to good yields. Coupling of chloropurine with a chiral aziridinyl diester is applied in the synthesis of a potential adenylosuccinate lyase inhibitor. 相似文献
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The anabolic action of intermittent parathyroid hormone on cortical bone depends partly on its ability to induce nitric oxide‐mediated vasorelaxation in BALB/c mice
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S Gohin A Carriero C Chenu AA Pitsillides TR Arnett M Marenzana 《Cell biochemistry and function》2016,34(2):52-62
There is strong evidence that vasodilatory nitric oxide (NO) donors have anabolic effects on bone in humans. Parathyroid hormone (PTH), the only osteoanabolic drug currently approved, is also a vasodilator. We investigated whether the NO synthase inhibitor L‐NAME might alter the effect of PTH on bone by blocking its vasodilatory effect. BALB/c mice received 28 daily injections of PTH[1–34] (80 µg/kg/day) or L‐NAME (30 mg/kg/day), alone or in combination. Hindlimb blood perfusion was measured by laser Doppler imaging. Bone architecture, turnover and mechanical properties in the femur were analysed respectively by micro‐CT, histomorphometry and three‐point bending. PTH increased hindlimb blood flow by >30% within 10 min of injection (P < 0.001). Co‐treatment with L‐NAME blocked the action of PTH on blood flow, whereas L‐NAME alone had no effect. PTH treatment increased femoral cortical bone volume and formation rate by 20% and 110%, respectively (P < 0.001). PTH had no effect on trabecular bone volume in the femoral metaphysis although trabecular thickness and number were increased and decreased by 25%, respectively. Co‐treatment with L‐NAME restricted the PTH‐stimulated increase in cortical bone formation but had no clear‐cut effects in trabecular bone. Co‐treatment with L‐NAME did not affect the mechanical strength in femurs induced by iPTH. These results suggest that NO‐mediated vasorelaxation plays partly a role in the anabolic action of PTH on cortical bone. © 2016 The Authors. Cell Biochemistry and Function published by John Wiley & Sons, Ltd. 相似文献
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Barends TR Polderman-Tijmes JJ Jekel PA Hensgens CM de Vries EJ Janssen DB Dijkstra BW 《The Journal of biological chemistry》2003,278(25):23076-23084
alpha-Amino acid ester hydrolases (AEHs) catalyze the hydrolysis and synthesis of esters and amides with an alpha-amino group. As such, they can synthesize beta-lactam antibiotics from acyl compounds and beta-lactam nuclei obtained from the hydrolysis of natural antibiotics. This article describes the gene sequence and the 1.9-A resolution crystal structure of the AEH from Xanthomonas citri. The enzyme consists of an alpha/beta-hydrolase fold domain, a helical cap domain, and a jellyroll beta-domain. Structural homology was observed to the Rhodococcus cocaine esterase, indicating that both enzymes belong to the same class of bacterial hydrolases. Docking of a beta-lactam antibiotic in the active site explains the substrate specificity, specifically the necessity of an alpha-amino group on the substrate, and explains the low specificity toward the beta-lactam nucleus. 相似文献
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During bacterial protein synthesis, stalled ribosomes can be rescued by tmRNA, a molecule with both tRNA and mRNA features. The tRNA region of tmRNA has sequence similarity with tRNA(Ala) and also has a clover-leaf structure folded similarly as in canonical tRNAs. Here we propose the L-shape of tmRNA to be stabilized by two tertiary interactions between its D- and T-loop on the basis of phylogenetic and experimental evidence. Mutational analysis clearly demonstrates a tertiary interaction between G(13) and U(342). Strikingly, this in evolution conserved interaction is not primarily important for tmRNA alanylation and for binding to elongation factor Tu, but especially for a proper functioning of SmpB. 相似文献
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Structural variation and functional importance of a D-loop-T-loop interaction in valine-accepting tRNA-like structures of plant viral RNAs
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de Smit MH Gultyaev AP Hilge M Bink HH Barends S Kraal B Pleij CW 《Nucleic acids research》2002,30(19):4232-4240
Valine-accepting tRNA-like structures (TLSs) are found at the 3′ ends of the genomic RNAs of most plant viruses belonging to the genera Tymovirus, Furovirus, Pomovirus and Pecluvirus, and of one Tobamovirus species. Sequence alignment of these TLSs suggests the existence of a tertiary D-loop–T-loop interaction consisting of 2 bp, analogous to those in the elbow region of canonical tRNAs. The conserved G18·Ψ55 pair of regular tRNAs is found to covary in these TLSs between G·U (possibly also modified to G·Ψ) and A·G. We have mutated the relevant bases in turnip yellow mosaic virus (TYMV) and examined the mutants for symptom development on Chinese cabbage plants and for accumulation of genetic reversions. Development of symptoms is shown to rely on the presence of either A·G or G·U in the original mutants or in revertants. This finding supports the existence and functional importance of this tertiary interaction. The fact that only G·U and A·G are accepted at this position appears to result from steric and energetic limitations related to the highly compact nature of the elbow region. We discuss the implications of these findings for the various possible functions of the valine-accepting TLS. 相似文献
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Turnip yellow mosaic virus (TYMV) has a genomic plus-strand RNA with a 5' cap followed by overlapping and different reading frames for the movement protein and polyprotein, while the distal coat protein cistron is translated from a subgenomic RNA. The 3'-untranslated region harbors a tRNA-like structure (TLS) to which a valine moiety can be added and it is indispensable for virus viability. Here, we report about a surprising interaction between TYMV-RNA-programmed ribosomes and 3'-valylated TLS that yields polyprotein with the valine N terminally incorporated by a translation mechanism resistant to regular initiation inhibitors. Disruption of the TLS exclusively abolishes polyprotein synthesis, which can be restored by adding excess TLS in trans. Our observations imply a novel eukaryotic mechanism for internal initiation of mRNA translation. 相似文献
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Nuclear gene trees and the phylogenetic relationships of the mangabeys (Primates: Papionini) 总被引:3,自引:1,他引:2
Phylogenetic relationships of mangabeys within the Old World monkey tribe
Papionini are inferred from analyses of nuclear DNA sequences from five
unlinked loci. The following conclusions are strongly supported, based on
congruence among trees derived for the five separate gene regions: (1)
mangabeys are polyphyletic within the Papionini; (2) Cercocebus is the
sister taxon to the genus Mandrillus; and (3) Lophocebus belongs to a clade
with Papio and Theropithecus, with Papio as its most likely sister taxon.
Morphologically based phylogenies positing mangabey monophyly were
evaluated by mapping the sequences for each locus on these trees. The data
seem to fit these trees poorly in both maximum-parsimony and likelihood
analyses. Incongruence among nuclear gene trees occurred in the
interrelationships among Lophocebus, Papio, and Theropithecus. Several
factors that may account for this incongruence are discussed, including
sampling error, random lineage sorting, and introgression.
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PPCMatrix: a PowerPC dotmatrix program to compare large genomic sequences against protein sequences 总被引:1,自引:0,他引:1
Summary : An interactive dotmatrix program for the MacOS was designed that
allows comparison of DNA to protein sequences using nested 3-frame
translations. Availability : Shareware, available at
http://copan.bioz.unibas.ch/software/ Contact : burglin@ubaclu. unibas.ch
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