1kig: Difference between revisions

[[Image:1kig.jpg|left|200px]]<br /><applet load="1kig" size="350" color="white" frame="true" align="right" spinBox="true"  

The structure of recombinant tick anticoagulant peptide (rTAP) complexed to bovine factor Xa at 3.0 A resolution reveals the structural basis for the specificity and the high affinity of rTAP. Three N-terminal residues, Tyr501, Asn502 and Arg503, play a critical role in the complex formation as suggested by earlier mutagenic studies and the ornithodorin-thrombin complex. Unexpectedly, the side-chain of Tyr501 is located in the S1 pocket, although factor Xa favors arginine as a P1 residue. Arg503 is located at the aryl binding pocket and forms a salt-bridge with Glu97 of factor Xa. The autolysis loop, which is disordered in the uninhibited factor Xa structure, is involved in the formation of the complex as a part of the secondary binding site. The C-terminal helix of rTAP interacts with factor Xa as a secondary binding determinant. The N-terminal residues of rTAP reorganize during the formation of the factor Xa-rTAP complex from the conformation found in the solution into an extended conformation. The presence of the secondary binding site confirms the proposed two-step kinetic mechanism based on the results of a mutagenesis study.

1KIG is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] and [http://en.wikipedia.org/wiki/Ornithodoros_moubata Ornithodoros moubata]. Active as [http://en.wikipedia.org/wiki/Coagulation_factor_Xa Coagulation factor Xa], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.21.6 3.4.21.6] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KIG OCA].  

[[Category: Chang, C H.]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:34:34 2008''