Partial purification of trypsin inhibitors from Parkia seeds (Fabaceae)

Abstract

Leguminous seeds (Fabaceae) have a high content of inhibitors of which serine protease inhibitors are the most widely studied. However, there are only a few studies related to the investigation of these proteins in tree species belonging to the Amazon flora. The protein content presented in seeds of four Amazonian Leguminosae species, Parkia pendula, P. discolor, P. multijuga and P. Nitida, was extracted by using NaCl 0.15 mol L-1 and then partially fractionated by using affinity chromatography performed on a trypsin-Sepharose 4B. These inhibitors presented different affinities between trypsin and chymotrypsin serine proteases, showing a higher inhibition to trypsin compared to chymotrypsin, except for P. nitida, which showed high inhibition against both enzymes. The SDS-PAGE analysis showed that the species from Parkia genus have a main band corresponding to partially purified trypsin inhibitors. The apparent molecular mass inhibitors (approximately 13-18 kDa) and the high specificity for trypsin suggest the occurrence of Bowman-Birk and Kunitz type inhibitors.

Sementes de leguminosas (Fabaceae) apresentam alto conteúdo de inibidores, incluindo os inibidores de serinoproteinases que têm sido extensivamente estudados. Todavia, poucos estudos foram realizados quanto à investigação dessas proteínas em espécies arbóreas pertencentes à flora amazônica. As proteínas presentes nas sementes de quatro espécies de leguminosas da Amazônia, Parkia pendula, P. discolor, P. multijuga e P. nitida, foram obtidas pela extração usando NaCl 0.15 mol L-1 e, parcialmente purificadas usando a cromatografia de afinidade em tripsina-Sepharose 4B. Os inibidores exibiram afinidades diferentes entre a tripsina e a quimotripsina, exceto para P. nitida, a qual apresentou alta inibição contra as duas enzimas. A análise em SDS-PAGE mostrou que as espécies do gênero Parkia contém uma banda principal correspondendo aos inibidores de tripsina parcialmente purificados. As massas moleculares aparentes determinadas para os inibidores (aproximadamente, 13 a 18 kDa) e a alta especificidade pela tripsina sugerem a ocorrência de inibidores do tipo Bowman-Birk e Kunitz.