1nb5
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(New page: 200px<br /> <applet load="1nb5" size="450" color="white" frame="true" align="right" spinBox="true" caption="1nb5, resolution 2.4Å" /> '''Crystal structure of...)
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Revision as of 16:13, 12 November 2007
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Crystal structure of stefin A in complex with cathepsin H
Overview
Binding of cystatin-type inhibitors to papain-like exopeptidases cannot be, explained by the stefin B-papain complex. The crystal structure of human, stefin A bound to an aminopeptidase, porcine cathepsin H, has been, determined in monoclinic and orthorhombic crystal forms at 2.8A and 2.4A, resolutions, respectively. The asymmetric unit of each form contains four, complexes. The structures are similar to the stefin B-papain complex, but, with a few distinct differences. On binding, the N-terminal residues of, stefin A adopt the form of a hook, which pushes away cathepsin H, mini-chain residues and distorts the structure of the short four residue, insertion (Lys155A-Asp155D) unique to cathepsin H. Comparison with the, structure of isolated cathepsin H shows that the rims of the cathepsin H, structure are slightly displaced (up to 1A) from their position in the, free enzyme. Furthermore, comparison with the stefin B-papain complex, showed that molecules of stefin A bind about 0.8A deeper into the active, site cleft of cathepsin H than stefin B into papain. The approach of, stefin A to cathepsin H induces structural changes along the interaction, surface of both molecules, whereas no such changes were observed in the, stefin B-papain complex. Carboxymethylation of papain seems to have, prevented the formation of the genuine binding geometry between a, papain-like enzyme and a cystatin-type inhibitor as we observe it in the, structure presented here.
About this Structure
1NB5 is a Protein complex structure of sequences from Homo sapiens and Sus scrofa. Active as Cathepsin H, with EC number 3.4.22.16 Full crystallographic information is available from OCA.
Reference
Crystal structure of Stefin A in complex with cathepsin H: N-terminal residues of inhibitors can adapt to the active sites of endo- and exopeptidases., Jenko S, Dolenc I, Guncar G, Dobersek A, Podobnik M, Turk D, J Mol Biol. 2003 Feb 21;326(3):875-85. PMID:12581647
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