PDBsum entry 4boh

Hydrolase/inhibitor

PDB id: 4boh

Contents

Protein chains

249 a.a.

28 a.a.

32 a.a.

Ligands

ALA-LYS-PRO-ARG-LEU

NAG ×2

SO4 ×5

Metals

_NA ×2

Waters ×92

PDB id:

4boh

Name:

Hydrolase/inhibitor

Title:

Madanins (merops i53) are cleaved by thrombin and factor xa

Structure:

Thrombin heavy chain. Chain: a, h. Synonym: alpha-thrombin, coagulation factor ii,. Thrombin light chain. Chain: b, l. Synonym: alpha-thrombin, coagulation factor ii. Thrombin inhibitor madanin 1. Chain: m. Fragment: residues 20-79.

Source:

Homo sapiens. Human. Organism_taxid: 9606. Tissue: plasma. Haemaphysalis longicornis. Organism_taxid: 44386. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.60Å R-factor: 0.193 R-free: 0.239

Authors:

A.C.Figueiredo,D.Desanctis,P.J.B.Pereira

Key ref:

A.C.Figueiredo et al. (2013). The tick-derived anticoagulant madanin is processed by thrombin and factor Xa. Plos One, 8, e71866. PubMed id: 23951260 DOI: 10.1371/journal.pone.0071866

Date:

20-May-13 Release date: 04-Sep-13

Protein chains

P00734  (THRB_HUMAN) -  Prothrombin from Homo sapiens

Seq: 622 a.a.

Struc: 249 a.a.

Protein chain

P00734  (THRB_HUMAN) -  Prothrombin from Homo sapiens

Seq: 622 a.a.

Struc: 28 a.a.

Protein chain

P00734  (THRB_HUMAN) -  Prothrombin from Homo sapiens

Seq: 622 a.a.

Struc: 32 a.a.

Enzyme reactions

• Enzyme class: Chains A, B, H, L: E.C.3.4.21.5 - thrombin.
• Reaction: Preferential cleavage: Arg-|-Gly; activates fibrinogen to fibrin and releases fibrinopeptide A and B.

DOI no: 10.1371/journal.pone.0071866

Plos One 8:e71866 (2013)

PubMed id: 23951260

The tick-derived anticoagulant madanin is processed by thrombin and factor Xa.

A.C.Figueiredo, D.de Sanctis, P.J.Pereira.

ABSTRACT

The cysteine-less peptidic anticoagulants madanin-1 and madanin-2 from the bush tick Haemaphysalis longicornis are the founding members of the MEROPS inhibitor family I53. It has been previously suggested that madanins exert their functional activity by competing with physiological substrates for binding to the positively charged exosite I (fibrinogen-binding exosite) of α-thrombin. We hereby demonstrate that competitive inhibition of α-thrombin by madanin-1 or madanin-2 involves binding to the enzyme's active site. Moreover, the blood coagulation factors IIa and Xa are shown to hydrolyze both inhibitors at different, although partially overlapping cleavage sites. Finally, the three-dimensional structure of the complex formed between human α-thrombin and a proteolytic fragment of madanin-1, determined by X-ray crystallography, elucidates the molecular details of madanin-1 recognition and processing by the proteinase. Taken together, the current findings establish the mechanism of action of madanins, natural anticoagulants that behave as cleavable competitive inhibitors of thrombin.