A trypsin inhibitor from Peltophorum dubium seeds active against pest proteases and its effect on the survival of Anagasta kuehniella (Lepidoptera: Pyralidae)

• Published in: Biochimica et biophysica acta Vol. 1621; no. 2; pp. 170 - 182
• Main Authors: Rodrigues Macedo, Maria Lı́gia, Machado Freire, Maria das Graças, Cabrini, Elaine Cristina, Toyama, Marcos H, Novello, José Camillo, Marangoni, Sérgio
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 02.05.2003
• Subjects: Amino Acid Sequence; Anagasta kuehniella; Animals; Drug Stability; Fabaceae - chemistry; Isoelectric Point; Lepidoptera - drug effects; Lepidoptera - enzymology; Molecular Sequence Data; Molecular Weight; Peltophorum dubium; Pest protease; Resistance; Seeds - chemistry; Trypsin inhibitor; Trypsin Inhibitors - chemistry; Trypsin Inhibitors - isolation & purification; Trypsin Inhibitors - pharmacology; Pest protease; Resistance; Peltophorum dubium; Trypsin inhibitor; Anagasta kuehniella
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/S0304-4165(03)00055-2

A novel trypsin inhibitor was purified from the seeds of Peltophorum dubium (Spreng.). SDS-PAGE under reducing conditions showed that the inhibitor consisted of a single polypeptide chain (ca. 20 kDa). The dissociation constants of 4×10 −10 and 1.6×10 −10 M were obtained with bovine and porcine trypsin, respectively. This constant was lower (2.6×10 −7 M) for chymotrypsin. The inhibitory activity was stable over a wide range of temperature and pH and in the presence of DTT. The N-terminal sequence of the P. dubium inhibitor showed a high degree of homology with other Kunitz-type inhibitors. When fed to the insect Anagasta kuehniella, in an artificial diet (inhibitor concentration 1.6%), the inhibitor produced ∼56% and delayed the development of this lepidopteran. The concentration of inhibitor in the diet necessary to cause a 50% reduction in the weight (ED50) of fourth instar larvae was ∼1%. The action of the P. dubium trypsin inhibitor (PDTI) on A. kuehniella may involve inhibition of the trypsin-like activity present in the larval midgut, resistance of the inhibitor to digestion by midgut enzymes and bovine trypsin, and association of the inhibitor with a chitin column and chitinous structures in the peritrophic membrane and/or midgut of the insect.