The C-terminal binding domain of hirullin P18: Antithrombin activity and comparison to hirudin peptides

• Published in: FEBS letters Vol. 269; no. 2; pp. 425 - 429
• Main Authors: Krstenansky, John L., Owen, Thomas J., Yates, Mark T., Mao, Simon J.T.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 03.09.1990; Elsevier
• Subjects: Amino Acid Sequence; Analytical, structural and metabolic biochemistry; animal physiology; biochemical phenomena; Biological and medical sciences; Freshwater; Fundamental and applied biological sciences. Psychology; Hirudin; Hirudinaria manillensis; Hirudins - pharmacology; Hirullin P18; Humans; Kinetics; Miscellaneous; Molecular Sequence Data; peptides; Peptides - chemical synthesis; Peptides - genetics; Peptides - pharmacology; Proteins; Sequence Homology, Nucleic Acid; Structure-Activity Relationship; Synthetic peptide; Thrombin; Thrombin - antagonists & inhibitors; AAA, amino acid analysis; HP18, N α-acetylhirullin P18 40–61; Pip, l-pipecolic acid; Bzl, benzyl; DMF, N,N-dimethylformainide; Hirullin P18; Thrombin; 2-C1Z, 2-chlorobenzyloxycarbonyl; DCM, dichloromethane; Hyp, 4-hydroxy- l-proline; HPLC, high performance liquid chromatography; Hirudin; HOBT, 1-hydroxybenzotriazole; Tos, tosyl; Boc, t-butoxycarbonyl; FAB-MS, fast-atom bombardment mass spectrometry; pNA, p-nitroanilide; Synthetic peptide; DCC, N,N'-dicyclohexylcarbodiimide; Chx, cyclohexyl; Proteins; C terminal peptide; Enzyme inhibitor; Binding site; Chemical synthesis; Biological activity; Ultraviolet visible spectrometry
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(90)81208-6

Hirullin P18 is a 61-amino acid hirudin-related protein having potent antithrombin activity. Similar to hirudin, it contains a highly acidic C-terminus, but has a significantly different sequence from any other known hirudin variant. The present study demonstrates that the C-terminal fragment acetyl-hirullin P18 40–61 possesses an antithrombin potency similar to that of acetyl-desulfatohirudin 45–65. Additionally, like the hirudin fragment analog, it inhibits fibrin-clot formation by binding to a non-catalytic site on thrombin. Sequential shortening of the hirullin P18 C-terminal fragment demonstrates the critical nature of Phe 51, which corresponds to the important Phe 56 residue of hirudin. Although the sequences of hirullin P18 54–61 and hirudin 59–65 have substantial differences, the C-terminal functional domain represented by hirullin P18 50–61 appears to be comparable to hirudin 55–65 in terms of its functional role in antithrombin activity.