Thrombin synthesis

Serpins were first identified as a set of proteins able to inhibit proteases. The name serpin is derived from this activity serine protease inhibitors . Heparin is a mixture of polysaccharides that bind to antithrombin in, inducing an allosteric change that greatly enhances its inhibition of thrombin synthesis. Some surgical patients, especially those receiving hip or heart valve replacements and those at risk of ischemic stroke (clots in the brain), are given heparin. 

The release of arachidonate and the synthesis or interconversion of eicosanoids can be initiated by a variety of stimuli, including histamine, hormones such as epinephrine and bradykinin, proteases such as thrombin, and even serum albumin. An important mechanism of arachidonate release and eicosanoid syn-... 

Endothelial cells are the major source of ET-1-synthesis. ET-1 is also produced by astrocytes, neurons, hepatocytes, bronchial epithelial cells, renal epithelial and mesangial cells. Physiological stimuli of ET-1-synthesis in endothelial cells are angiotensin II, catecholamines, thrombin, growth factors, insulin, hypoxia and shear stress. Inhibitors of ET-1 synthesis are atrial natriuretic peptide, prostaglandin E2 and prostacyclin. ET-2 is mainly synthesized in kidney, intestine, myocardium and placenta and ET-3 is predominantely produced by neurons, astrocytes and renal epithelial cells. 

Heparin inhibits the formation of fibrin clots, inhibits the conversion of fibrinogen to fibrin, and inactivates several of the factors necessary for the clotting of blood. Heparin cannot be taken orally because it is inactivated by gastric acid in the stomach therefore, it must be given by injection. Heparin has no effect on clots that have already formed and aids only in preventing the formation of new blood clots (thrombi). The LMWHs act to inhibit clotting reactions by binding to antithrombin HI, which inhibits the synthesis of factor Xa and the formation of thrombin. 

The marine natural product dynosin A (92) is a new member of the aerugi-nosin family and a novel inhibitor of thrombin and Factor Vila. In Hanessian s total synthesis of 92 [66], both the dihydroxyoctahydroindole 88 and the A3 pyrroline moiety 91 were prepared by RCM-based routes (Scheme 17). 

Frederick, R. Robert, S. Charlier, C. de Ruyck, J. Wouters, J. Masereel, B. Pochet, L. Mechanism-based thrombin inhibitors design, synthesis, and molecular docking of a new selective 2-OXO-2/7- l-benzopyxan derivative. J. Med. Chem. 2007, 50, 3645-3650. 

Wakselman, M. Mazaleyrat, J.-P. Lin, R. C. Xie, J. Vigier, B. Vilain, A. C. Fesquet, S. Boggetto, N. Reboud-Ravaux, M. Design, synthesis and study of a selective cyclopeptidic mechanism-based inhibitor of human thrombin. In Peptides Chemistry, Structure... 

Hartwig, J. H., Bokoch, G. M. etal. Thrombin receptor ligation and activated Rac uncap actin filament barbed ends through phosphoinositide synthesis in permeabilized human platelets. Cell 82 643-653,1995. 

V Caciagli, F Cardinali, F Bonelli, P Lombardi. Large-scale production of peptides using the solid phase continuous flow method. Part 2 Preparative synthesis of a 26-mer peptide thrombin inhibitor. J Pept Sci 4, 327, 1998. 

The last of the fat-soluble vitamins to be identified was vitamin K, found by Dam to be an anti-hemorrhagic factor for young chicks, distinct from vitamin C. Its structure was determined by Dam in collaboration with Karrer. Interest in the vitamin was intensified when it was discovered (Link, 1941) that dicoumarol, present in spoiled sweet clover, was the agent producing hypothrombinemia (giving prolonged blood-clotting time) in cattle. Since vitamin K is structurally similar to dicoumarol, the vitamin was presumptively implicated in thrombin formation. This has been fully substantiated by recent work on the role of vitamin K in the synthesis of prothrombin in the liver. 

S. D., Lucas, B.J., Gardell, S.J., Lyle, E.A., Appleby, S.D., Cook, J.J., FIolahan, M.A., Stranieri, M.T., Lynch,Y J., Lin, J.H., Chen, I.W., Vastag, K., Naylor-Olsen, A.M., and Vacca, J.P. Discovery and development of the novel potent orally active thrombin inhibitor N-(9-Hydroxy-9-fluorenecarboxy)prolyl tran s -4-amin ocycl ohexylmethyl ami de (L-372,460) coapplication of structure-based design and rapid multiple analog synthesis on solid support. 

Linusson, a., Gotteries, )., Olsson, T., Oernskov, E., Folestad, S., Noeden, B., and Wold, S. Statistical molecular design, parallel synthesis, and biological evaluation of a library of thrombin inhibitors. /. Med. Chem. 2001, 44, 3424-3439. 

Another method for reducing osmolality of the injection was achieved by the synthesis of mono-carboxylic dimers, leading to the development of ioxaglic acid (600 mOsm kg at 320 mgl mL ). Because of specific properties on platelet functions and thrombin generation, this agent is widely used for interventional procedures [3]. 

In the extravascular pathway (right), tissue thromboplastin (factor 111), a membrane protein in the deeper layers of the vascular wall, activates coagulation factor Vll. The activated form of this (Vila) autocatalytically promotes its own synthesis and also generates the active factors IXa and Xa from their precursors. With the aid of factor Villa, PL, and Ca factor IXa produces additional Xa, which finally— with the support of Va, PL, and Ca ""—releases active thrombin. 

Active thrombin not only converts fibrinogen into fibrin, but also indirectly promotes its own synthesis by catalyzing the activation of factors V and Vlll. In addition, it catalyzes the activation of factor Xlll and thereby triggers the cross-linking of the fibrin. 

Backes BJ, Harris JL, Leonetti F, et al. Synthesis of positional-scanning hbraries of fluorogenic peptide substrates to define the extended substrate specificity of plasmin and thrombin. Nat Biotechnol 2000 18 187-93. 

Substrates include benzyl (2 g) and cinnamyl (2.7 g) alcohols to acids cyclopentanol (1 g), benzhydrol (3.9 g), benzoin (4 g), pantolactone (2.6 g) to ketones (RuCy TCCA/( Bu N)Br/aq. Kj(C03)/CH3CN) (Fig. 2.14) [25] [[2-[2-hydroxypropyl) amino]-l,2-dioxoethyl]amino]acetic acid ethyl ester (6.21 kg) to [(l,2-dioxo-2-oxopropyl)amino]ethyl)amino] acetic acid ethyl ester, part of the industrial-scale synthesis of thrombin inhibitor (RuCyaq. Na(BrOj)/CH3CN) [166] (H-)-dihydroc-holesterol (8 g) to cholest-3-one (RuO /aq. K(10 )/(BTEAC)/CHCl3) [308] ... 

Iwanowicz EJ, Lau WF, Lin J, Roberts DGM, Seiler SM. Retro-binding tripeptide thrombin active inhibitors discovery, synthesis and molecular modeling. J Med Chem 1994 37 2122-2124. 

Hilpert , Ackermann J, Banner DW, Gast A, Gubemator K, Hadvary P, Labler L, Muller K, Schmid G, Tschopp T, van de Waterbeemd H. Design and synthesis of potent and highly selective thrombin inhibitors. J Med Chem 1994 37 3889-3901. 

Vermeer, C. (1990) y-Carboxyglutamate-containing proteins and the vitamin K-dependent carboxylase. Biochem. J. 266, 625-636. Describes the biochemical basis for the requirement of vitamin K in blood clotting and the importance of carboxylation in the synthesis of the blood-clotting protein thrombin. 

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