Purification and biochemical characterization of a serine proteinase inhibitor from Derris trifoliata Lour. seeds: insight into structural and antimalarial features.
Phytochemistry
; 70(6): 703-12, 2009 Apr.
Article
em En
| MEDLINE
| ID: mdl-19409579
ABSTRACT
A potent serine proteinase inhibitor was isolated and characterized from the seeds of the tropical legume liana, Derris trifoliata (DtTCI) by ammonium sulfate precipitation, ion exchange chromatography and gel filtration chromatography. SDS-PAGE as well as MALDI-TOF analysis showed that DtTCI is a single polypeptide chain with a molecular mass of approximately 20 kDa. DtTCI has three isoinhibitors (pI 4.55, 5.34 and 5.72) and, inhibited both trypsin and chymotrypsin in a 11 molar ratio. Both Dixon plots and Lineweaver-Burk double reciprocal plots revealed a competitive inhibition of trypsin and chymotrypsin activity, with inhibition constants (K(i)) of 1.7x10(-10) and 1.25x10(-10) M, respectively. N-terminal sequence of DtTCI showed over 50% similarity with numerous Kunitz-type inhibitors of the Papilionoideae subfamily. High pH amplitude and broad temperature optima were noted for DtTCI, and time course experiments indicated a gradual loss in inhibitory potency on treatment with dithiothreitol (DTT). Circular Dichroism (CD) spectrum of native DtTCI revealed an unordered structure whereas exposure to thermal-pH extremes, DTT and guanidine hydrochloride (Gdn HCl) suggested that an abundance of beta-sheets along with intramolecular disulfide bonds provide conformational stability to the active site of DtTCI, and that severity of denaturants cause structural modifications promoting inhibitory inactivity. Antimalarial studies of DtTCI indicate it to be a potent antiparasitic agent.
Texto completo:
1
Coleções:
01-internacional
Temas:
Geral
Base de dados:
MEDLINE
Assunto principal:
Sementes
/
Inibidores de Serina Proteinase
/
Derris
/
Antimaláricos
Idioma:
En
Revista:
Phytochemistry
Ano de publicação:
2009
Tipo de documento:
Article
País de afiliação:
Índia