Crystal structure of a peptidyl pyridinium methyl ketone inhibitor with thrombin
Research article published in Biochemistry (1995)
Abstract
The crystal structure of a complex between a bivalent peptidyl pyridinium methyl ketone inhibitor and human alpha-thrombin has been solved and refined at 2.0 A to an R factor of 0.18. The inhibitor, (D)cyclohexylalanine-Pro-Arg-(CH2N+C5H4CH2CO)-(Gly)4-Asp- Tyr-Glu-Pro-Ile-Pro-Glu-Glu-Ala-cyclo-hexylalanine-(D)Glu (coded P596), which forms a reversible covalent complex with thrombin, is highly potent with a Ki = 4.6 +/- 1.0 x 10(-14) M, lower than that of recombinant hirudin. The N-terminal, active-site-directed portion of the inhibitor is linked to the fibrinogen recognition exosite binding portion by a tetraglycine segment. The strong electron-withdrawing effect provided by the permanent positive charge on the pyridinium nitrogen makes the arginyl carbonyl carbon more susceptible to nucleophilic attack. In the crystal, a covalent P596-thrombin complex is observed. The electron density surrounding the active site portion and the pyridinium of the inhibitor is very well defined, clearly showing the existence of a covalent bond between the Ser195 O gamma and the now tetrahedral carbon of the inhibitor. The decreased binding ability of thrombin inhibitors containing N-terminal acetylation is discussed as is the effect of replacing the P3 (D)phenylalanine with (D)cyclohexylalanine. The electron density surrounding the remainder of the inhibitor is generally well defined, the exceptions being the C-terminal (D)Glu, the highly flexible tetraglycine linker, and some of the solvent-directed side chains.(ABSTRACT TRUNCATED AT 250 WORDS)
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Resumen
The crystal structure of a complex between a bivalent peptidyl pyridinium methyl ketone inhibitor and human alpha-thrombin has been solved and refined at 2.0 A to an R factor of 0.18.
Por qué esto importa para la hirudoterapia
Este artículo reporta la estructura cristalina de un inhibidor bivalente peptidílico de metilcetona de piridinio (codificado como P596) en complejo con alfa-trombina humana, resuelta y refinada a 2,0 Å con un factor R de 0,18. El resumen describe que P596 forma un complejo covalente reversible con la trombina con una Ki de 4,6 × 10⁻¹⁴ M, indicada como inferior a la de la hirudina recombinante, con una porción dirigida al sitio activo enlazada a una porción de unión al exositio de reconocimiento de fibrinógeno mediante un segmento de tetraglicina. Para ASH, la relevancia es indirecta: la hirudina recombinante se utiliza únicamente como comparador de referencia para la potencia inhibitoria. La advertencia es que se trata de un estudio puramente estructural de un inhibidor sintético; no están involucradas sanguijuelas, hirudina completa ni componentes del secretoma de la sanguijuela.
Citación
Crystal structure of a peptidyl pyridinium methyl ketone inhibitor with thrombin
Rehse PH et al. · Biochemistry, 1995
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Añadido a la biblioteca ASH: May 27, 2026 · Última actualización del sitio: 18 de junio de 2026