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Inhibition of trypsin by cowpea thionin: Characterization, molecular modeling, and docking
Author(s) -
Melo Francislete R.,
Rigden Daniel J.,
Franco Octávio L.,
Mello Luciane V.,
Ary Maria B.,
Grossi de Sá Maria F.,
Bloch Carlos
Publication year - 2002
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.10142
Subject(s) - vigna , trypsin , docking (animal) , chymotrypsin , biochemistry , chemistry , molecular mass , trypsin inhibitor , biology , enzyme , botany , medicine , nursing
Higher plants produce several families of proteins with toxic properties, which act as defense compounds against pests and pathogens. The thionin family represents one family and comprises low molecular mass cysteine‐rich proteins, usually basic and distributed in different plant tissues. Here, we report the purification and characterization of a new thionin from cowpea ( Vigna unguiculata ) with proteinase inhibitory activity. Cowpea thionin inhibits trypsin, but not chymotrypsin, binding with a stoichiometry of 1:1 as shown with the use of mass spectrometry. Previous annotations of thionins as proteinase inhibitors were based on their erroneous identification as homologues of Bowman‐Birk family inhibitors. Molecular modeling experiments were used to propose a mode of docking of cowpea thionin with trypsin. Consideration of the dynamic properties of the cowpea thionin was essential to arrive at a model with favorable interface characteristics comparable with structures of trypsin‐inhibitor complexes determined by X‐ray crystallography. In the final model, Lys11 occupies the S1 specificity pocket of trypsin as part of a canonical style interaction. Proteins 2002;48:311–319. © 2002 Wiley‐Liss, Inc.