A trypsin inhibitor from Peltophorum dubium seeds active against pest proteases and its effect on the survival of Anagasta kuehniella (Lepidoptera: Pyralidae).
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 x 10(-10) and 1.6 x 10(-10) M were obtained with bovine and porcine trypsin, respectively. This constant was lower (2.6 x 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 approximately 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 approximately 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.
Departamento de Ciências Naturais, Universidade Federal de Mato Grosso do Sul, CP 210, CEP 79603-011, Três Lagoas, MS, Brazil. bioplant@terra.com.br
Maria Lígia
ML
Rodrigues Macedo
Maria das Graças
Md
Machado Freire
Elaine Cristina
EC
Cabrini
Marcos H
MH
Toyama
José Camillo
JC
Novello
Sérgio
S
Marangoni
D000595:Amino Acid Sequence; D000818:Animals; D004355:Drug Stability; D007887:Fabaceae / Q000737:chemistry*; D007526:Isoelectric Point; D007915:Lepidoptera / Q000187:drug effects* / Q000201:enzymology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D012639:Seeds / Q000737:chemistry*; D014361:Trypsin Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*
D014361:Trypsin Inhibitors