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81.
Xiaohua Chen L. Zhu Xiaozeng You Nenad M. Kostić 《Journal of biological inorganic chemistry》1998,3(1):1-8
Dipeptides and tripeptides AcMet-aaH containing N-acetyl methionine, in which the group aaH is GlyH, AlaH, ValH, or Gly-GlyH, undergo hydrolytic cleavage of the Met-aaH peptide
bond in the presence of the following complexes of palladium(II): cis-[Pd(en)(H2O)2]2+, cis-[Pd(tn)(H2O)2]2+, cis-[Pd(en)(CH3OH)2]2+, cis-[Pd(S,N-MetH)(H2O)2]2+, cis-[Pd(S,N-Met-GlyH)(H2O)2]2+, and cis-[Pd(S,N-Met-AlaH)(H2O)2]2+. These mononuclear complexes are precursors of binuclear palladium(II) complexes containing the substrates AcMet-aaH as bridging
thioether ligands. The rate constant for cleavage is higher when the bidentate ligand in the precursor complex is ethylenediamine
(which is completely displaced) than S,N-methionine (of which only the amino group is displaced), because the number of aqua ligands available for cleavage is greater
in the former than in the latter case. The demonstrated dependence of the rate constant on the steric bulk (volume) of the
leaving group, aaH, points the way toward achieving a degree of sequence selectivity in cleavage of peptide bonds by palladium(II)
aqua complexes. One equivalent of cis-[Pd(en)(H2O)2]2+ cleaves as many as ten equivalents of AcMet-GlyH, but the rate constant decreases as the molar excess of the dipeptide over
the catalyst increases. This demonstration of catalytic turnover points the way to our ultimate goal – artificial metallopeptidases.
Received: 13 June 1997 / Accepted: 24 September 1997 相似文献
82.
Sarah G. Earle Mariya Lobanovska Hayley Lavender Changyan Tang Rachel M. Exley Elisa Ramos-Sevillano Douglas F. Browning Vasiliki Kostiou Odile B. Harrison Holly B. Bratcher Gabriele Varani Christoph M. Tang Daniel J. Wilson Martin C. J. Maiden 《PLoS pathogens》2021,17(10)
Many invasive bacterial diseases are caused by organisms that are ordinarily harmless components of the human microbiome. Effective interventions against these microbes require an understanding of the processes whereby symbiotic or commensal relationships transition into pathology. Here, we describe bacterial genome-wide association studies (GWAS) of Neisseria meningitidis, a common commensal of the human respiratory tract that is nevertheless a leading cause of meningitis and sepsis. An initial GWAS discovered bacterial genetic variants, including single nucleotide polymorphisms (SNPs), associated with invasive meningococcal disease (IMD) versus carriage in several loci across the meningococcal genome, encoding antigens and other extracellular components, confirming the polygenic nature of the invasive phenotype. In particular, there was a significant peak of association around the fHbp locus, encoding factor H binding protein (fHbp), which promotes bacterial immune evasion of human complement by recruiting complement factor H (CFH) to the meningococcal surface. The association around fHbp with IMD was confirmed by a validation GWAS, and we found that the SNPs identified in the validation affected the 5’ region of fHbp mRNA, altering secondary RNA structures, thereby increasing fHbp expression and enhancing bacterial escape from complement-mediated killing. This finding is consistent with the known link between complement deficiencies and CFH variation with human susceptibility to IMD. These observations demonstrate the importance of human and bacterial genetic variation across the fHbp:CFH interface in determining IMD susceptibility, the transition from carriage to disease. 相似文献
83.
Kontargiris E Kolettas E Vadalouca A Trougakos IP Gonos ES Kalfakakou V 《Cell research》2004,14(5):415-422
Local anesthetics inhibit cell proliferation and induce apoptosis in various cell types. Ropivacaine, a unique, novel tertiary amine-type anesthetic, was shown to inhibit the proliferation of several cell types including keratinocytes. We found that Ropivacaine could inhibit the proliferation and induce apoptosis in an immortalized human keratinocyte line,HaCaT, in a dose- and time-dependent manner and with the deprivation of serum. The dose-dependent induction of apoptosis by ropivacaine was demonstrated by DNA fragmentation analysis and the proteolytic cleavage of a caspase-3 substrate—poly (ADP-ribose) polymerase (PARP). In addition, ropivacaine downregulated the expression of clusterin/ apoliporotein J, a protein with anti-apoptotic properties, in a dose-dependent manner, which well correlated with the induction of apoptosis of HaCaT cells. To investigate the role of clusterin/apoliporotein J in ropivacaine-induced apoptosis,HaCaT cells overexpressing clusterin/apoliporotein J were generated and compared to cells expressing the well established anti-apoptotic Bcl-2 protein. Ectopic overexpression of the secreted form of clusterin/apoliporotein J or Bcl-2decreased the sensitivity of HaCaT cells to toxic effects of ropivacaine as demonstrated by DNA fragmentation, the proteolytic cleavage of PARP and by a reduction in procaspase-3 expression. Furthermore, the downregulation of endogenous clusterin/apolipoprotein J levels by ropivacaine suggested that this might be one mechanism by which ropivacaine induced cell death in HaCaT cells. In conclusion, the ability of ropivacaine to induce antiproliferative responses and to suppress the expression of the anti-apoptotic protein clusterin/apolipoprotein J, combined with previously reported anti-inflammatory activity and analgesic property of the drug, suggests that ropivacaine may have potential utility in the local treatment of tumors. 相似文献
84.
Petropoulou V Garrigue-Antar L Kadler KE 《The Journal of biological chemistry》2005,280(24):22616-22623
Bone morphogenetic protein 1 (BMP-1), which is a tolloid member of the astacin-like family of zinc metalloproteinases, is a highly effective procollagen C-proteinase (PCP) and chordinase. On the other hand, mammalian tolloid like-2 (mTLL-2) does not cleave chordin or procollagen; procollagen is cleaved by mTLL-2 in the presence of high levels of procollagen C-proteinase enhancer-1 (PCPE-1), for reasons that are unknown. We used these differences in activity between BMP-1 and mTLL-2 to narrow in on the domains in BMP-1 that specify PCP and chordinase activity. Using a domain swap approach, we showed that: 1) the metalloproteinase and CUB2 domains of BMP-1 are absolutely required for PCP activity; swaps with either of the corresponding domains in BMP-1 and mTLL-2 did not result in procollagen cleavage and 2) the proteinase domain of mTLL-2 can cleave chordin if coupled to the CUB1 domain of BMP-1. Therefore, the minimal structure for chordinase activity comprises a metalloproteinase domain (either from BMP-1 or from mTLL-2) and the CUB1 domain of BMP-1 (the CUB1 domain of mTLL-2 cannot substitute for the CUB1 domain of BMP-1). We showed that the minimal procollagen C-proteinase (BMP-1 lacking the EGF and CUB3 domain) was enhanced by PCPE-1 but not as well as BMP-1 retaining the CUB3 domain. Further studies showed that PCPE-1 had no effect on the ability of BMP-1 to cleave chordin. The data support a previously suggested mechanism of PCPE-1 whereby PCPE-1 interacts with procollagen, but in addition, the CUB3 domain of BMP-1 appears to augment the interaction. 相似文献
85.
Anesti V McDonald IR Ramaswamy M Wade WG Kelly DP Wood AP 《Environmental microbiology》2005,7(8):1227-1238
Diverse methylotrophic bacteria were isolated from the tongue, and supra- and subgingival plaque in the mouths of volunteers and patients with periodontitis. One-carbon compounds such as dimethylsulfide in the mouth are likely to be used as growth substrates for these organisms. Methylotrophic strains of Bacillus, Brevibacterium casei, Hyphomicrobium sulfonivorans, Methylobacterium, Micrococcus luteus and Variovorax paradoxus were characterized physiologically and by their 16S rRNA gene sequences. The type strain of B. casei was shown to be methylotrophic. Enzymes of methylotrophic metabolism were characterized in some strains, and activities consistent with growth using known pathways of C1-compound metabolism demonstrated. Genomic DNA from 18 tongue and dental plaque samples from nine volunteers was amplified by the polymerase chain reaction using primers for the 16S rRNA gene of Methylobacterium and the mxaF gene of methanol dehydrogenase. MxaF was detected in all nine volunteers, and Methylobacterium was detected in seven. Methylotrophic activity is thus a feature of the oral bacterial community. 相似文献
86.
Papandreou V Magiatis P Kalpoutzakis E Skaltsounis AL Harvala C 《Zeitschrift für Naturforschung. C, Journal of biosciences》2002,57(3-4):235-238
A new glycoside of salicylic aldehyde, paeonicluside, was isolated from the roots of the Greek endemic species Paeonia clusii subsp. clusii and identified as alpha-L-arabinopyranosyl-(1-->6)-O-beta-D-glucopyranoside of salicylic aldehyde (1). In addition, one characteristic monoterpene and two monoterpene glycosides were identified as paeoniflorigenone, paeoniflorin and benzoyl paeoniflorin, respectively. The structure of 1 was elucidated on the basis of its spectroscopic data and chemical correlation. It is the first time that a derivative of salicylic aldehyde is isolated from the well-studied Paeonia genus. 相似文献
87.
Stéphanie Cherqui Vasiliki Kalatzis Lionel Forestier Isabelle Poras Corinne Antignac 《BMC genomics》2000,1(1):2-5
Background
Cystinosis is an autosomal recessive disorder characterised by an intralysosomal accumulation of cystine, and affected individuals progress to end-stage renal failure before the age of ten. The causative gene, CTNS, was cloned in 1998 and the encoded protein, cystinosin, was predicted to be a lysosomal membrane protein. 相似文献88.
Vasiliki Daraki Vaggelis Georgiou Stathis Papavasiliou Georgia Chalkiadaki Marianna Karahaliou Stella Koinaki Katerina Sarri Maria Vassilaki Manolis Kogevinas Leda Chatzi 《PloS one》2015,10(5)
ContextMaternal pre-pregnancy obesity may increase the risk of childhood obesity but it is unknown whether other metabolic factors in early pregnancy such as lipid profile and hypertension are associated with offspring cardiometabolic traits.ObjectiveOur objective was to investigate whether fasting lipid, glucose, and insulin levels during early pregnancy and maternal pre-pregnancy weight status, are associated with offspring adiposity measures, lipid levels and blood pressure at preschool age.ResultsPre-pregnancy overweight/obesity was associated with greater risk of offspring overweight/obesity (RR: 1.83, 95%CI: 1.19, 2.81), central adiposity (RR: 1.97, 95%CI: 1.11, 3.49), and greater fat mass by 5.10mm (95%CI: 2.49, 7.71) at 4 years of age. These associations were more pronounced in girls. An increase of 40mg/dl in fasting serum cholesterol levels in early pregnancy was associated with greater skinfold thickness by 3.30mm (95%CI: 1.41, 5.20) at 4 years of age after adjusting for pre-pregnancy BMI and several other confounders. An increase of 10mmHg in diastolic blood pressure in early pregnancy was associated with increased risk of offspring overweight/obesity (RR: 1.22, 95%CI: 1.03, 1.45), and greater skinfold thickness by 1.71mm (95% CI: 0.57, 2.86) at 4 years of age.ConclusionsMetabolic dysregulation in early pregnancy may increase the risk of obesity at preschool age. 相似文献
89.
Paola Cipriani Paola Di Benedetto Piero Ruscitti Daniela Verzella Mariafausta Fischietti Francesca Zazzeroni Vasiliki Liakouli Francesco Carubbi Onorina Berardicurti Edoardo Alesse Roberto Giacomelli 《Arthritis research & therapy》2015,17(1)
IntroductionSystemic sclerosis (SSc) is a complex and not fully understood autoimmune disease associated with fibrosis of multiple organs. The main effector cells, the myofibroblasts, are collagen-producing cells derived from the activation of resting fibroblasts. This process is regulated by a complex repertoire of profibrotic cytokines, and among them transforming growth factor beta (TGF-β) and endothelin-1 (ET-1) play a major role. In this paper we show that TGF-β and ET-1 receptors co-operate in myofibroblast activation, and macitentan, an ET-1 receptor antagonist binding ET-1 receptors, might interfere with both TGF-β and ET-1 pathways, preventing myofibroblast differentiation.MethodsFibroblasts isolated from healthy controls and SSc patients were treated with TGF-β and ET-1 and successively analyzed for alpha smooth muscle actin (α-SMA) and collagen (Col1A1) expression and for the Sma and Mad Related (SMAD) phosphorylation. We further tested the ability of macitentan to interfere with these process. Furthermore, we silenced ET-1 and endothelin-1 receptor A expression and evaluated the formation of an ET-1/TGF-β receptor complex by immunoprecitation assay.ResultsWe showed myofibroblast activation in SSc fibroblasts assessing the expression of α-SMA and Col1A1, after stimulation with TGF-β and ET-1. Macitentan interfered with both ET-1- and TGF-β-induced fibroblast activation. To explain this unexpected inhibitory effect of macitentan on TGF-β activity, we silenced ET-1 expression on SSc fibroblasts and co-immunoprecipitated these two receptors, showing the formation of an ET-1/TGF-β receptor complex.ConclusionsDuring SSc, ET-1 produced by activated endothelia contributes to myofibroblast activation using TGF-β machinery via an ET-1/TGF-β receptor complex. Macitentan interferes with the profibrotic action of TGF-β, blocking the ET-1 receptor portion of the ET-1/TGF-β receptor complex. 相似文献
90.
Meromit Singer Idit Kosti Lior Pachter Yael Mandel-Gutfreund 《Nucleic acids research》2015,43(7):3498-3508
DNA methylation is an important epigenetic marker associated with gene expression regulation in eukaryotes. While promoter methylation is relatively well characterized, the role of intragenic DNA methylation remains unclear. Here, we investigated the relationship of DNA methylation at exons and flanking introns with gene expression and histone modifications generated from a human fibroblast cell-line and primary B cells. Consistent with previous work we found that intragenic methylation is positively correlated with gene expression and that exons are more highly methylated than their neighboring intronic environment. Intriguingly, in this study we identified a unique subset of hypomethylated exons that demonstrate significantly lower methylation levels than their surrounding introns. Furthermore, we observed a negative correlation between exon methylation and the density of the majority of histone modifications. Specifically, we demonstrate that hypo-methylated exons at highly expressed genes are associated with open chromatin and have a characteristic histone code comprised of significantly high levels of histone markings. Overall, our comprehensive analysis of the human exome supports the presence of regulatory hypomethylated exons in protein coding genes. In particular our results reveal a previously unrecognized diverse and complex role of the epigenetic landscape within the gene body. 相似文献