1jqg
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(New page: 200px<br /><applet load="1jqg" size="450" color="white" frame="true" align="right" spinBox="true" caption="1jqg, resolution 2.5Å" /> '''Crystal Structure of ...)
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Revision as of 21:56, 24 November 2007
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Crystal Structure of the Carboxypeptidase A from Helicoverpa Armigera
Overview
The cotton bollworm Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae), is one of the most serious insect pests in Australia, India and China. The, larva causes substantial economical losses to legume, fibre, cereal, oilseed and vegetable crops. This pest has proven to be difficult to, control by conventional means, mainly due to the development of pesticide, resistance. We present here the 2.5 A crystal structure from the novel, procarboxypeptidase (PCPAHa) found in the gut extracts from H. armigera, larvae, the first one reported for an insect. This metalloprotease is, synthesized as a zymogen of 46.6 kDa which, upon in vitro activation with, Lys-C endoproteinase, yields a pro-segment of 91 residues and an active, carboxypeptidase moiety of 318 residues. Both regions show a, three-dimensional structure quite similar to the corresponding structures, in mammalian digestive carboxypeptidases, the most relevant structural, differences being located in the loops between conserved secondary, structure elements, including the primary activation site. This activation, site contains the motif (Ala)(5)Lys at the C terminus of the helix, connecting the pro- and the carboxypeptidase domains. A remarkable feature, of PCPAHa is the occurrence of the same (Ala)(6)Lys near the C terminus of, the active enzyme. The presence of Ser255 in PCPAHa instead of Ile and Asp, found in the pancreatic A and B forms, respectively, enlarges the S1', specificity pocket and influences the substrate preferences of the enzyme., The C-terminal tail of the leech carboxypeptidase inhibitor has been, modelled into the PCPAHa active site to explore the substrate preferences, and the enzymatic mechanism of this enzyme.
About this Structure
1JQG is a Single protein structure of sequence from Helicoverpa armigera with ZN as ligand. Active as Carboxypeptidase A, with EC number 3.4.17.1 Full crystallographic information is available from OCA.
Reference
Crystal structure of a novel mid-gut procarboxypeptidase from the cotton pest Helicoverpa armigera., Estebanez-Perpina E, Bayes A, Vendrell J, Jongsma MA, Bown DP, Gatehouse JA, Huber R, Bode W, Aviles FX, Reverter D, J Mol Biol. 2001 Oct 26;313(3):629-38. PMID:11676544
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