Dabigatran Attenuates the Binding of Thrombin to Platelets-A Novel Mechanism of Action.

Background:  Thrombin is a multifunctional regulatory enzyme of the haemostasis and has both pro- and anticoagulant roles. It has, therefore, been a main target for drug discovery over many decades. Thrombin is a serine protease and possesses two positively charged regions called exosites, through which it is known to bind to many substrates.

Associations between hemostatic markers and mortality in COVID-19 - Compounding effects of D-dimer, antithrombin and PAP complex.

In this single-center cohort study, we applied a panel of laboratory markers to characterize hemostatic function in 217 consecutive patients that underwent testing for COVID-19 as they were admitted to Linköping University Hospital between April and June 2020. In the 96 patients that tested positive for SARS-CoV-2 (COVID-19+), the cumulative incidences of death and venous thromboembolism were 24.0% and 19.

Effects of Heparin and Bivalirudin on Thrombin-Induced Platelet Activation: Differential Modulation of PAR Signaling Drives Divergent Prothrombotic Responses.

Heparin and bivalirudin are widely used as anticoagulants in the setting of acute thrombosis. In this study, we investigated how these drugs affect the ability of thrombin to generate a prothrombotic platelet response via activation of the protease-activated receptors (PARs) 1 and 4. We examined the effects of heparin/antithrombin and bivalirudin on PAR1- and PAR4-mediated intracellular calcium mobilization, aggregation, α-granule release, and procoagulant membrane exposure in platelets exposed to thrombin concentrations likely to be encountered in the thrombus microenvironment during thrombosis.

Platelet function testing at low platelet counts: When can you trust your analysis?

Background: Although flow cytometry is often brought forward as a preferable method in the setting of thrombocytopenia, the relative effects of low sample counts on results from flow cytometry-based platelet function testing (FC-PFT) in comparison with light transmission aggregometry (LTA) and multiple electrode aggregometry (MEA) has not been reported.

Objectives: To compare the effects of different sample platelet counts (10, 50, 100, and 200 × 10 L) on platelet activation measured with FC-PFT, LTA, and MEA using the same anticoagulant and agonist concentrations as for the commercial MEA test.

Methods: Platelets were stimulated with two commonly used platelet agonists (ADP [6.

Gradient-dependent inhibition of stimulatory signaling from platelet G protein-coupled receptors.

As platelet activation is an irreversible and potentially harmful event, platelet stimulatory signaling must be tightly regulated to ensure the filtering-out of inconsequential fluctuations of agonist concentrations in the vascular milieu. Herein, we show that platelet activation via G protein-coupled receptors is gradient-dependent, i.e.

Important amino acid residues of hexachlorocyclohexane dehydrochlorinases (LinA) for enantioselective transformation of hexachlorocyclohexane isomers.

LinA-type1 and LinA-type2 are two well-characterized variants of the enzyme 'hexachlorocyclohexane (HCH)-dehydrochlorinase'. They differ from each other at ten amino acid positions and exhibit differing enantioselectivity for the transformation of the (-) and (+) enantiomers of α-HCH. Amino acids responsible for this enantioselectivity, however, are not known.

Role of a repeated hexapeptide motif GIHFAP near C-terminus in assembly, stability, and activity of "HCH dehydrochlorinase LinA".

Enzyme "hexachlorocyclohexane (HCH) dehydrochlorinase LinA" mediates first step of aerobic microbial degradation of a chlorinated insecticide γ-HCH. The archetypal LinA-type1 consists of 156 amino acids that include a directly repeated hexapeptide motif GIHFAP at positions 141-146 and 148-153. Analysis of a series of LinA mutants, containing none, one, two, or three units of this repeated motif revealed that two units, as present in wild-type LinA, are required for its optimal activity and stability.

Crystal structure of the hexachlorocyclohexane dehydrochlorinase (LinA-type2): mutational analysis, thermostability and enantioselectivity.

Hexachlorocyclohexane dehydrochlorinase (LinA) mediates dehydrochlorination of γ-HCH to 1, 3, 4, 6-tetrachloro-1,4-cyclohexadiene that constitutes first step of the aerobic degradation pathway. We report the 3.5 Å crystal structure of a thermostable LinA-type2 protein, obtained from a soil metagenome, in the hexagonal space group P6(3)22 with unit cell parameters a = b = 162.

Isolation of a novel thermostable dehydrochlorinase (LinA) from a soil metagenome.

Hexachlorocyclohexane dehydrochlorinase (LinA) mediates first step of aerobic degradation of a chlorinated insecticide γ-hexachlorocyclohexane (γ-HCH). In this study, we describe characterization of a novel variant (LinA-type2) that is distinct from reported LinAs and is substantially more thermostable than archetypal LinA-UT26. LinA-type2 remains active even after 8 h of incubation at 45 °C, when nearly 50% activity of LinA-UT26 is lost after incubation for 60 min at the same temperature.

Selective loss of lin genes from hexachlorocyclohexane-degrading Pseudomonas aeruginosa ITRC-5 under different growth conditions.

The chlorinated insecticide gamma-hexachlorocyclohexane (gamma-HCH) is sequentially metabolized by the products of linA, linB, linC, linD, linE, and linF genes to beta-ketoadipate, which is subsequently mineralized. Two or more copies of these genes are present in the bacterium Pseudomonas aeruginosa ITRC-5 that was isolated earlier by selective enrichment on technical-HCH. At least one copy of linA, linB, linC, linD, and possibly linE is lost from ITRC-5 upon its growth on gamma-HCH.