Primary structure of Dioclea glabra trypsin inhibitor, DgTI, a Bowman-Birk inhibitor. |
| |
Authors: | N R Bueno H Fritz E A Auerswald R Mentele M Sampaio C A Sampaio M L Oliva |
| |
Institution: | Departamento de Bioquímica, Universidade Federal de S?o Paulo-Escola Paulista de Medicina, Rua Três de Maio, 100, S?o Paulo, SP, 04044-020, Brazil. |
| |
Abstract: | A novel serine proteinase inhibitor, DgTI, was purified from Dioclea glabra seeds by acetone precipitation, and ion-exchange and reverse phase chromatography. The inhibitor belongs to the Bowman-Birk family, and its primary sequence, determined by Edman degradation and mass spectrometry, of 67 amino acids is: SSGPCCDRCRCTKSEPPQCQCQDVRLNSCHSACEACVCSHSMPGLCSCLDITHFCHEPCKSSGDDED++ +. Although two reactive sites were determined by susceptibility to trypsin (Lys(13) and His(40)), the inhibitory function was assigned only to the first site. The inhibitor forms a 1:1 complex with trypsin, and Ki is 0.5 x 10(-9) M. Elastase, chymotrypsin, kallikreins, factor Xa, thrombin, and plasmin were not inhibited. By its properties, DgTI is a Bowman-Birk inhibitor with structural and inhibitory properties between the class of Bowman-Birk type I (with a fully active second reactive site), and Bowman-Birk type II (devoid of second reactive site). |
| |
Keywords: | |
|
|