These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Selective inhibition of trypsins by insect peptides: role of P6-P10 loop.
    Author: Kellenberger C, Ferrat G, Leone P, Darbon H, Roussel A.
    Journal: Biochemistry; 2003 Nov 25; 42(46):13605-12. PubMed ID: 14622007.
    Abstract:
    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).
    [Abstract] [Full Text] [Related] [New Search]