Monoclonal antibodies against soybean Bowman-Birk inhibitor recognize the protease-reactive loops.

Monoclonal antibodies against soybean Bowman-Birk protease inhibitor (BBI) have been generated and used to detect and quantify BBI in foods, soybean germplasm, and animal tissues and fluids. The purpose of this study was to determine the recognition sites of two monoclonal antibodies to BBI (mAb 238 and mAb 217) in relation to the protease-inhibitory sites of BBI. The results showed that (1) the binding of mAb 238 can be blocked by trypsin and that of mAb 217 by chymotrypsin; (2) the trypsin or chymotrypsin inhibitory activities of BBI are blocked by mAb 238 or mAb 217, respectively; and (3) mAb 238 failed to recognize a tryptic loop mutant BBI variant and mAb 217 was unable to bind a chymotryptic loop mutant BBI variant. These findings demonstrate that the epitopes recognized by mAb 238 and mAb 217 reside, at least in part, in the tryptic and chymotryptic loops of BBI, respectively.

Mutations within the protein Z-dependent protease inhibitor gene are associated with venous thromboembolic disease: a new form of thrombophilia.

Protein Z-dependent protease inhibitor (ZPI) is a serpin that inhibits the activated coagulation factors X and XI. The precise physiological significance of ZPI in the control of haemostasis is unknown although a deficiency of ZPI may be predicted to alter this balance. The coding region of the ZPI gene was screened for mutations using denaturing high-performance liquid chromatography. 16 mutations/polymorphisms within the coding region of ZPI were identified including two mutations, which generated stop codons at residues R67 and W303. We observed nonsense mutations within the ZPI gene in 4.4% of thrombosis patients (n = 250) compared with 0.8% of controls (n = 250). The difference in distribution of stop codon mutations between thrombosis patients and controls was significant (P = 0.02) with an odds ratio of 5.7 (95% confidence interval, 1.25-26.0). Our results suggest an association between ZPI deficiency and venous thrombosis and we propose that ZPI deficiency is potentially a new form of thrombophilia.