Discovery of SCH446211 (SCH6): a new ketoamide inhibitor of the HCV NS3 serine protease and HCV subgenomic RNA replication.

Introduction of various modified prolines at P(2) and optimization of the P(1) side chain led to the discovery of SCH6 (24, Table 2), a potent ketoamide inhibitor of the HCV NS3 serine protease. In addition to excellent enzyme potency (K(i)*= 3.8 nM), 24 was also found to be a potent inhibitor of HCV subgenomic RNA replication with IC(50) and IC(90) of 40 and 100 nM, respectively.

The role of ISAba1 in expression of OXA carbapenemase genes in Acinetobacter baumannii.

ISAba1 was found in all widespread clones of Acinetobacter baumannii in the United Kingdom. All isolates studied had a blaOXA-51-like carbapenemase gene; some also had blaOXA-23-like and/or blaOXA-58-like. Among isolates with blaOXA-51-like as sole carbapenemase gene, only those with ISAba1 adjacent to blaOXA-51-like were carbapenem resistant.

PoPS: a computational tool for modeling and predicting protease specificity.

Proteases play a fundamental role in the control of intra- and extracellular processes by binding and cleaving specific amino acid sequences. Identifying these targets is extremely challenging. Current computational attempts to predict cleavage sites are limited, representing these amino acid sequences as patterns or frequency matrices.

Hydroxylated analogues of the orally active broad spectrum antifungal, Sch 51048 (1), and the discovery of posaconazole [Sch 56592; 2 or (S,S)-5].

As part of a detailed study, the syntheses, biological activities, and pharmacokinetic properties of hydroxylated analogues of the previously described broad spectrum antifungal agents, Sch 51048 (1), Sch 50001 (3), and Sch 50002 (4), are described. Based on an overall superior profile, one of the alcohols, Sch 56592 (2), was selected for clinical studies.

Serpins 2005 - fun between the beta-sheets. Meeting report based upon presentations made at the 4th International Symposium on Serpin Structure, Function and Biology (Cairns, Australia).

Serpins are the largest family of protease inhibitors and are fundamental for the control of proteolysis in multicellular eukaryotes. Most eukaryote serpins inhibit serine or cysteine proteases, however, noninhibitory members have been identified that perform diverse functions in processes such as hormone delivery and tumour metastasis. More recently inhibitory serpins have been identified in prokaryotes and unicellular eukaryotes, nevertheless, the precise molecular targets of these molecules remains to be identified.

Control of the coagulation system by serpins. Getting by with a little help from glycosaminoglycans.

Members of the serine protease inhibitor (serpin) superfamily play important roles in the inhibition of serine proteases involved in complex systems. This is evident in the regulation of coagulation serine proteases, especially the central enzyme in this system, thrombin. This review focuses on three serpins which are known to be key players in the regulation of thrombin: antithrombin and heparin cofactor II, which inhibit thrombin in its procoagulant role, and protein C inhibitor, which primarily inhibits the thrombin/thrombomodulin complex, where thrombin plays an anticoagulant role.

Elucidation of the substrate specificity of the C1s protease of the classical complement pathway.

The complement system is a central component of host defense but can also contribute to the inflammation seen in pathological conditions. The C1s protease of the first complement component, the C1 complex, initiates the pathway. In this study we have elucidated the full specificity of the enzyme for the first time using a randomized phage display library.

An immune response directed to proteinase and adhesin functional epitopes protects against Porphyromonas gingivalis-induced periodontal bone loss.

Porphyromonas gingivalis, a pathogen associated with periodontitis, bound to fibrinogen, fibronectin, hemoglobin, and collagen type V with a similar profile to that of its major virulence factor, the cell surface RgpA-Kgp proteinase-adhesin complex. Using peptide-specific, purified Abs in competitive inhibition ELISAs and epitope mapping assays, we have identified potential adhesin binding motifs (ABMs) of the RgpA-Kgp complex responsible for binding to host proteins. The RgpA-Kgp complex and synthetic ABM and proteinase active site peptides conjugated to diphtheria toxoid, when used as vaccines, protected against P.

The murine orthologue of human antichymotrypsin: a structural paradigm for clade A3 serpins.

Antichymotrypsin (SERPINA3) is a widely expressed member of the serpin superfamily, required for the regulation of leukocyte proteases released during an inflammatory response and with a permissive role in the development of amyloid encephalopathy. Despite its biological significance, there is at present no available structure of this serpin in its native, inhibitory state. We present here the first fully refined structure of a murine antichymotrypsin orthologue to 2.

PoPS: a computational tool for modeling and predicting protease specificity.

Proteases play a fundamental role in the control of intra- and extra-cellular processes by binding and cleaving specific amino acid sequences. Identifying these targets is extremely challenging. Current computational attempts to predict cleavage sites are limited, representing these amino acid sequences as patterns or frequency matrices.

Hepatitis C virus NS3-4A serine protease inhibitors: SAR of P'2 moiety with improved potency.

We have discovered that introduction of appropriate amino acid derivatives at P'2 position improved the binding potency of P3-capped alpha-ketoamide inhibitors of HCV NS3 serine protease. X-ray crystal structure of one of the inhibitors (43) bound to the protease revealed the importance of the P'2 moiety.

Detection and typing of integrons in epidemic strains of Acinetobacter baumannii found in the United Kingdom.

Integrons were sought in Acinetobacter isolates from hospitals in the United Kingdom by integrase gene PCR. Isolates were compared by pulsed-field gel electrophoresis, and most belonged to a small number of outbreak strains or clones of A. baumannii, which are highly successful in the United Kingdom.

The role of protease-activated receptor-1 in bone healing.

Protease-activated receptor (PAR)-1, a G-protein-coupled receptor activated by thrombin, mediates thrombin-induced proliferation of osteoblasts. The current study was undertaken to define the role of PAR-1 in bone repair. Holes were drilled transversely through the diaphysis of both tibiae of PAR-1-null and wild-type mice.

The C-terminal domains of the gingipain K polyprotein are necessary for assembly of the active enzyme and expression of associated activities.

The Porphyromonas gingivalis lysine-specific cysteine protease (gingipain K, Kgp) is expressed as a large precursor protein consisting of a leader sequence, a pro-fragment, a catalytic domain with a C-terminal IgG-like subdomain (IgSF) and a large haemagglutinin/adhesion (HA) domain. In order to directly study the role of these non-catalytic domains in pro-Kgp processing and maturation in P. gingivalis, the wild-type form of the gene was replaced with deletion variants encoding C-terminally truncated proteins, including KgpDeltaHA3/4 (Delta1292-1732 aa), KgpDeltaHA2-4 (Delta1157-1732 aa), KgpDeltaHA1-4 (Delta738-1732 aa), KgpDeltaC-term/HA (Delta681-1732 aa) and KgpDeltaIg/C-term/HA (602-1732 aa).

Characterisation of viridans group streptococci with different levels of Tet(M)-mediated tetracycline resistance.

Streptococcus oralis 264-3, Streptococcus mitis 254-1 and S. mitis 264-1, isolated from the oral cavities of two children were each found to carry the tet(M) gene but exhibited different degrees of reduced susceptibility to tetracycline (tetracycline MICs of 2, 8 and 64 mg/L, respectively). The aim of this study was to determine the molecular basis for the different levels of tetracycline resistance (Tc(R)) observed.

Studies on the receptors mediating responses of osteoblasts to thrombin.

The serine protease thrombin stimulates proliferation in osteoblasts, but decreases alkaline phosphatase (ALP) activity, a marker of osteoblast differentiation. Three thrombin receptors have been identified, protease activated receptor (PAR)-1, PAR-3 and PAR-4; we have previously demonstrated that mouse osteoblasts express PAR-1 and PAR-4. The effect of thrombin on osteoblast proliferation and differentiation was studied to determine which of the thrombin receptors is responsible for the primary effects of thrombin.

Community and hospital spread of Escherichia coli producing CTX-M extended-spectrum beta-lactamases in the UK.

Objectives: During 2003, the Health Protection Agency's Antibiotic Resistance Monitoring and Reference Laboratory began to receive isolates of Escherichia coli for confirmation of extended-spectrum beta-lactamase production with a phenotype implying a CTX-M-type beta-lactamase, i.e. MICs of cefotaxime > or = 8-fold higher than MICs of ceftazidime.

Mercuric resistance genes in gram-positive oral bacteria.

Mercury-resistant bacteria isolated from the oral cavities of children carried one of two types of merA gene that appear to have evolved from a common ancestor. Streptococcus oralis, Streptococcus mitis and a few other species had merA genes that were very similar to merA of Bacillus cereus strain RC607. Unlike the B.

Activation of protease-activated receptor-2 leads to inhibition of osteoclast differentiation.

Unlabelled: PAR-2 is expressed by osteoblasts and activated by proteases present during inflammation. PAR-2 activation inhibited osteoclast differentiation induced by hormones and cytokines in mouse bone marrow cultures and may protect bone from uncontrolled resorption.

Introduction: Protease-activated receptor-2 (PAR-2), which is expressed by osteoblasts, is activated specifically by a small number of proteases, including mast cell tryptase and factor Xa.

Physical characterization of serpin conformations.

The native serpin fold is characterized by being metastable. This thermodynamic characteristic is manifested in the conversion of the native state to other more stable conformations. Whilst this structural transition is required for proteinase inhibition and regulation of a range of biological phenomena, inappropriate structural changes can result in a number of disease states.

Antithrombin: in control of coagulation.

Antithrombin is a serine proteinase inhibitor (serpin) which controls the process of coagulation. It has a well defined structure, consisting of three beta-sheets, nine alpha-helices and a reactive centre loop (RCL). The RCL contains the reactive centre which harbours a bait sequence for target proteases; cleavage results in inhibition by a unique mechanism.

Importance of the prime subsites of the C1s protease of the classical complement pathway for recognition of substrates.

The classical complement pathway, which plays a vital role in preventing infection, is initiated by the action of the serine proteases C1r and C1s. We have examined the hydrolysis of substrates representing cleavage sequences in the physiological substrates for C1s, C2 and C4. These studies showed that the P(1)'-P(4)' substrate residues of C2 and C4 conferred greater affinity of substrate for enzyme and also induced a sigmoidal dependence of enzyme velocity on substrate concentration.

Cloning and expression of the major secreted cathepsin B-like protein from juvenile Fasciola hepatica and analysis of immunogenicity following liver fluke infection.

The functions of the cathepsin B-like proteases in liver flukes are unknown and analysis has been hindered by a lack of protein for study, since the protein is produced in small amounts by juvenile flukes. To circumvent this, we isolated and characterized a cDNA encoding the major secreted cathepsin B from Fasciola hepatica. The predicted preproprotein is 339 amino acids in length, with the mature protease predicted to be 254 amino acids long, and shows significant similarity to parasite and mammalian cathepsin B.