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1wo9
From Proteopedia
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Selective inhibition of trypsins by insect peptides: role of P6-P10 loop
Overview
PMP-D2 and HI, two peptides from Locusta migratoria, were shown to belong, to the family of tight-binding protease inhibitors. However, they interact, weakly with bovine trypsin (K(i) around 100 nM) despite a trypsin-specific, Arg at the primary specificity site P1. Here we demonstrate that they are, potent inhibitors of midgut trypsins isolated from the same insect and of, a fungal trypsin from Fusarium oxysporum (K(i) <or= 0.02 nM). Therefore, they display a selectivity not existing for the parent chymotrypsin, inhibitor PMP-C. By NMR, we demonstrate that HI possesses a highly rigid, structure similar to the crystal structure of a variant of PMP-D2 in, complex with bovine alpha-chymotrypsin. The main difference with PMP-C is, located in the region from residues 20 to 24 (positions P6-P10) that, interacts with the loop containing Gly173 in chymotrypsin. The, corresponding residue in mammalian trypsins is always a proline that may, generate a steric clash with the inhibitor. The residues thought to confer, selectivity were mutated with PMP-C as a model. The resulting analogue, PMP-D2(K10W,P21A,W25A) loses some activity toward insect and fungal, trypsins but is a more potent inhibitor of mammalian trypsins, corresponding to a decrease of selectivity. This work represents a first, attempt in tuning the selectivity of natural peptidic serine protease, inhibitors by mutating residues out of the reactive loop (P3-P'3).
About this Structure
1WO9 is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Selective inhibition of trypsins by insect peptides: role of P6-P10 loop., Kellenberger C, Ferrat G, Leone P, Darbon H, Roussel A, Biochemistry. 2003 Nov 25;42(46):13605-12. PMID:14622007
Page seeded by OCA on Sun Nov 25 00:24:28 2007
