Conformation of Bowman-Birk Inhibitor

Abstract

Bowman-Birk inhibitor, a major trypsin and chymotrypsin inhibitor from soybean, has 71 amino acids with 7 disulfide bonds. Conformation of Bowman-Birk inhibitor in native state, after heating, and after disulfide bonds were broken by sodium metabisulfite was determined by circular dichroism.The native Bowman-Birk inhibitor has 61% /3-sheet, 38% unordered form, 1% /3-turn, and no -helical structure. There was no significant change in conformation after Bowman-Birk inhibitor was heated at 80 °C for 1 h in phosphate buffer. There was a decrease in /3-sheet and an increase in /3-turn structure after Bowman-Birk inhibitor was heated at 80 °C for 1 h in sodium metabisulfite-phosphate buffer. Although the change in conformation after disulfide bonds of Bowman-Birk inhibitor were broken was statistically significant (P < 0.05), the magnitude of the change was not large. The data support Bowman-Birk inhibitor's having a stable conformation even after disulfide bonds are broken.

Crystal Structure of the Bifunctional Soybean Bowman‐Birk Inhibitor at 0.28‐nm Resolution

“…Hydrophobic collapse of the exposed hydrophobic patches into a regular hydrophobic core (reviewed by Lins and Brasseur, 1995) may be prevented by the array of seven disulfide bridges. This hypothesis is supported by the observation of considerable changes in the CD spectra of BBI under reducing conditions even in the absence of denaturant (Wu and Sessa, 1994).…”

Probing the Soybean Bowman–Birk Inhibitor Using Recombinant Antibody Fragments

“…The propensity for BBI to self-associate has previously been observed by us and others, with or without SDS, and in the presence of β-mercaptoethanol and urea. 3,9,31 After separation on the SDS-PAGE gel, proteins immunoprecipitated by magnetic particles were then analyzed by direct tandem mass spectrometry after in-gel digestion with trypsin and reversephase separation of the tryptic peptides. The prominent band was identified as the soybean trypsin inhibitor (Figure 6b).…”

Using Exogenous Enzymes to Increase the Nutritional Value of Soybean Meal in Poultry Diet

“…Protein solubility in a KOH solution has been proved a good indicator for monitoring over-processing of soybean meal (Araba and Dale, 1990). Other methods such as chemical treatments (Sessa et al, 1990;Wu and Sessa, 1994), chemical modification of disulfide bonds (Wang et al, 2009), fermentation (Feng et al, 2007) etc. were studied to explore the possibility to inactivate the activity of trypsin inhibitors, however, these methods still stay in research level so far.…”