1ae8: Difference between revisions

[[Image:1ae8.gif|left|200px]]<br /><applet load="1ae8" size="350" color="white" frame="true" align="right" spinBox="true"  

Kinetics, thermodynamics and structural aspects of human alpha-thrombin (thrombin) inhibition by newly synthesized low molecular weight derivatives of alpha-azalysine have been investigated. The thrombin catalyzed hydrolysis of N-ethoxycarbonyl-D-Phe-Pro-alpha-azaLys p-nitrophenyl ester (Eoc-D-Phe-Pro-azaLys-ONp) and N-carbobenzoxy-Pro-alpha-azaLys p-nitrophenyl ester (Cbz-Pro-azaLys-ONp) was investigated at pH 6.2 and 21.0 degrees C, and analyzed in parallel with that of N-alpha-(N,N-dimethylcarbamoyl)-alpha-azalysine p-nitrophenyl ester (Dmc-azaLys-ONp). Decarboxylation following the enzymatic hydrolysis of these p-nitrophenyl esters gave the corresponding 1-peptidyl-2(4-aminobutyl) hydrazines (peptidyl-Abh) showing properties of thrombin competitive inhibitors. Therefore, thermodynamics for the reversible binding of D-Phe-Pro-Abh, Cbz-Pro-Abh and Dmc-Abh to thrombin was examined. These results are consistent with the minimum four-step catalytic mechanism for product inhibition of serine proteinases. Eoc-D-Phe-Pro-azaLys-ONp and Eoc-D-Phe-Pro-Abh display a sub-micromolar affinity for thrombin together with a high selectivity versus homologous plasmatic and pancreatic serine proteinases acting on cationic substrates. The three-dimensional structures of the reversible non-covalent thrombin:Eoc-D-Phe-Pro-Abh and thrombin:Cbz-Pro-Abh complexes have been determined by X-ray crystallography at 2.0 A resolution (R-factor = 0.169 and 0.179, respectively), and analyzed in parallel with that of the thrombin:Dmc-azaLys acyl-enzyme adduct. Both Eoc-D-Phe-Pro-Abh and Cbz-Pro-Abh competitive inhibitors are accommodated in the thrombin active center, spanning the region between the aryl binding site and the S1 primary specificity subsite.

1AE8 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Hirudo_medicinalis Hirudo medicinalis] and [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=NAG:'>NAG</scene> and <scene name='pdbligand=AZL:'>AZL</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Thrombin Thrombin], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.21.5 3.4.21.5] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1AE8 OCA].  

[[Category: Simone, G De.]]

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