Crystal structure of a peptidyl pyridinium methyl ketone inhibitor with thrombin

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.

The 2.0 A structure of human alpha-thrombin bound to the bivalent inhibitor P596 reveals a covalent bond with Ser195 and a tetraglycine linker connecting the active-site portion to the fibrinogen recognition exosite; its potency exceeds recombinant hirudin.

Explore how this research connects to clinical practice

More peer-reviewed studies in Drug Development.

• Hirudotherapy in Medicine and Dentistry — Jha K et al. (2015)
• Leech therapy: a history — Hyson J (2005)
• Hirudins of the Asian medicinal leech, Hirudinaria manillensis: same same, but different — Lukas P et al. (2019)
• Transcriptomic analysis of the salivary gland of medicinal leech Hirudo nipponia — Lu Z et al. (2018)
• Molecular dynamic and pharmacological studies on protein-engineered hirudin variants of Hirudinaria manillensis and Hirudo medicinalis — Sun Y et al. (2022)
• Cell-free synthesis of the hirudin variant 1 of the blood-sucking leech Hirudo medicinalis — Wüstenhagen D et al. (2020)
• Hirudin variants production by genetic engineered microbial factory — Zhang J, Lan N (2018)
• Hirudin in heparin-induced thrombocytopenia — Lubenow N, Greinacher A (2002)
• Hirudin ameliorates diabetic nephropathy by inhibiting Gsdmd-mediated pyroptosis — Han J et al. (2023)
• Hirudin as alternative anticoagulant--a historical review — Markwardt F (2002)

Browse all ASH-analysed research →