1iwd

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spinqualitylabelsall models 1iwd, resolution 1.63Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Proposed Amino Acid Sequence and the 1.63 Angstrom X-ray Crystal Structure of a Plant Cysteine Protease Ervatamin B: Insight into the Structural Basis of its Stability and Substrate Specificity.

Overview

The crystal structure of a cysteine protease ervatamin B, isolated from, the medicinal plant Ervatamia coronaria, has been determined at 1.63 A., The unknown primary structure of the enzyme could also be traced from the, high-quality electron density map. The final refined model, consisting of, 215 amino acid residues, 208 water molecules, and a thiosulfate ligand, molecule, has a crystallographic R-factor of 15.9% and a free R-factor of, 18.2% for F > 2sigma(F). The protein belongs to the papain superfamily of, cysteine proteases and has some unique properties compared to other, members of the family. Though the overall fold of the structure, comprising two domains, is similar to the others, a few natural, substitutions of conserved amino acid residues at the interdomain cleft of, ervatamin B are expected to increase the stability of the protein. The, substitution of a lysine residue by an arginine (residue 177) in this, region of the protein may be important, because Lys --> Arg substitution, is reported to increase the stability of proteins. Another substitution in, this cleft region that helps to hold the domains together through hydrogen, bonds is Ser36, replacing a conserved glycine residue in the others. There, are also some substitutions in and around the active site cleft. Residues, Tyr67, Pro68, Val157, and Ser205 in papain are replaced by Trp67, Met68, Gln156, and Leu208, respectively, in ervatamin B, which reduces the volume, of the S2 subsite to almost one-fourth that of papain, and this in turn, alters the substrate specificity of the enzyme.

About this Structure

1IWD is a Single protein structure of sequence from Tabernaemontana divaricata with THJ as ligand. Full crystallographic information is available from OCA.

Reference

Proposed amino acid sequence and the 1.63 A X-ray crystal structure of a plant cysteine protease, ervatamin B: some insights into the structural basis of its stability and substrate specificity., Biswas S, Chakrabarti C, Kundu S, Jagannadham MV, Dattagupta JK, Proteins. 2003 Jun 1;51(4):489-97. PMID:12784208

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