Open AccessComparative structure analysis of proteinase inhibitors from the desert locust, Schistocerca gregaria
Author(s) -
Gáspári Zoltán,
Patthy András,
Gráf László,
Perczel András
Publication year - 2002
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.0014-2956.2001.02685.x
Subject(s) - schistocerca , antiparallel (mathematics) , chymotrypsin , chemistry , stereochemistry , serine proteinase inhibitors , desert locust , biochemistry , trypsin , enzyme , biology , locust , serine protease , protease , botany , physics , quantum mechanics , magnetic field
The solution structure of three small serine proteinase inhibitors, two natural and one engineered protein, SGCI␣( Schistocerca gregaria chymotrypsin inhibitor), SGCI[L30R, K31M] and SGTI ( Schistocerca gregaria trypsin inhibitor), were determined by homonuclear NMR‐spectroscopy. The molecules exhibit different specificities towards target proteinases, where SGCI is a good chymotrypsin inhibitor, its mutant is a potent trypsin inhibitor, and SGTI inhibits both proteinases weakly. Interestingly, SGTI is a much better inhibitor of insect proteinases than of the mammalian ones used in common assays. All three molecules have a similar fold composed from three antiparallel β‐pleated sheets with three disulfide bridges. The proteinase binding loop has a somewhat distinct geometry in all three peptides. Moreover, the stabilization of the structure is different in SGCI and SGTI. Proton–deuterium exchange experiments are indicative of a highly rigid core in SGTI but not in SGCI. We suggest that the observed structural properties play a significant role in the specificity of these inhibitors.