1pe6
From Proteopedia
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REFINED X-RAY STRUCTURE OF PAPAIN(DOT)E-64-C COMPLEX AT 2.1-ANGSTROMS RESOLUTION
Overview
E-64-c, a synthetic cysteine protease inhibitor designed from E-64, binds, to papain through a thioether covalent bond. The x-ray diffraction data, for 2.1-A resolution were used to determine the three-dimensional, structure of this complex and refined it to R = 0.159. 0.159. In the, complex structure, the configurational conversion from S to R took place, on the epoxy carbon of E-64-c, implying that the nucleophilic attack of, the Cys-25 thiol group occurs at the opposite side of the epoxy oxygen, atom. The leucyl and isoamylamide groups of E-64-c were strongly fixed to, papain S subsites by specific interactions, including hydrogen bonding to, the Gly-66 residue. The carboxyl-terminal anion of E-64-c formed an, electrostatic interaction with the protonated His-159 imidazole ring, (O-...HN+ = 3.76 A) and consequently prevented the participation of this, residue in the hydrolytic charge-relay system. No significant distortion, caused by the binding of E-64-c was shown in the secondary structure of, papain. It is important to note that inhibitor and substrate have opposite, binding modes for the peptide groups. The possible relationship between, the binding mode and inhibitory activity is discussed on the basis of the, crystal structure of this complex.
About this Structure
1PE6 is a Single protein structure of sequence from [1] with E6C and MOH as ligands. Active as Lyase, with EC number 4.3.22.2 Full crystallographic information is available from OCA.
Reference
Refined x-ray structure of papain.E-64-c complex at 2.1-A resolution., Yamamoto D, Matsumoto K, Ohishi H, Ishida T, Inoue M, Kitamura K, Mizuno H, J Biol Chem. 1991 Aug 5;266(22):14771-7. PMID:1860874
Page seeded by OCA on Tue Nov 20 23:43:49 2007
