Bowman-Birk soybean trypsin inhibitor, amino

Table VIII. Amino Acid Sequence Homology Among the Bowman-Birk Soybean Trypsin Inhibitor (BB 89)> Lima Bean Trypsin Inhibitor IV (LB 75) and Great Northern Bean Trypsin Inhibitor II (GB 90)...

Aprotinin is a polypeptide consisting of 58 amino acid residues derived from bovine lung tissues and shows inhibitory activity toward various proteolytic enzymes including chymo-trypsin, kallikrein, plasmin, and trypsin. It was also one of the first enzyme inhibitors used as an auxiliary agent for oral (poly)peptide administration. The co-administration of aprotinin led to an increased bioavailability of peptide and protein drugs [5,44,45], The Bowman-Birk inhibitor (71 amino acids, 8 kDa) and the Kunitz trypsin inhibitor (184 amino acids, 21 kDa) belong to the soybean trypsin inhibitors. Both are known to inhibit trypsin, chymotrypsin, and elastase, whereas carboxypeptidase A and B cannot be inhibited [7,46],... 

A family of cysteine proteinase inhibitors different from the cystatin superfamily was isolated from pineapple stem acetone powder. These inhibitors have a Mr of about 5800 and are composed of a longer (41 amino acids) and a shorter (11 amino acids) peptide chain connected with disulfide bonds [29]. The conserved sequence Gln-Val-Val-Ala-Gly of the cystatins is not present in these inhibitors, indicating a different mechanism of interaction. The bromelain inhibitor VI was found to share similar folding and disulfide bond connectivities with the Bowman-Birk trypsin/chymotrypsin inhibitor from soybean [30,31]. The physiological role of these inhibitors remains unclear. 

Soybean also contains the Bowman-Birk inhibitor, which consists of 78 amino acid residues (M, 8,000) and is much smaller than STI. It is a double headed inhibitor, i.e. in addition to inhibiting trypsin, it can simultaneously inhibit a second protease, e.g. chymo-trypsin. 

With soybean Bowman-Birk proteinase inhibitor, Odani and Ikenaka (1973) succeeded in separating two small fragments, one with 38 amino acids residues having a trypsin inhibitor activity, the other with 29 residues having a chymotrypsin inhibitor activity. However, reconstitution was not achieved. 

---