RESUMO

A second trypsin inhibitor (DMTI-II) was purified from the seed of Dimorphandra mollis (Leguminosae-Mimosoideae) by ammonium sulfate precipitation (30-60%), gel filtration, and ion-exchange and affinity chromatography. A molecular weight of 23 kDa was estimated by gel filtration on a Superdex 75 column SDS-PAGE under reduced conditions showed that DMTI-II consisted of a single polypeptide chain, although isoelectric focusing revealed the presence of three isoforms. The dissociation constant of 1.7 x 10(-9) M with bovine trypsin indicated a high affinity between the inhibitor and this enzyme. The inhibitory activity was stable over a wide pH range and in the presence of DTT. The N-terminal sequence of DMTI-II showed a high degree of homology with other Kunitz-type inhibitors.

Assuntos

Fabaceae/química , Sementes/química , Inibidores da Tripsina/isolamento & purificação , Inibidores da Tripsina/metabolismo , Tripsina/metabolismo , Animais , Ditiotreitol/metabolismo , Humanos , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/isolamento & purificação , Proteínas de Plantas/metabolismo , Especificidade por Substrato , Temperatura , Inibidores da Tripsina/química , Inibidores da Tripsina/genética