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Studies on simultaneous inhibition of trypsin and chymotrypsin by horsegram Bowman-Birk inhibitor

Balaji, Prakash and Murthy, M. R. N. and Sreerama, Y. N. and Rajagopal Rao, D. and Gowda, L. R. (1997) Studies on simultaneous inhibition of trypsin and chymotrypsin by horsegram Bowman-Birk inhibitor. Journal of Biosciences, 22 (5). pp. 545-554. ISSN 0021-8561

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Bowman-Birk inhibitors (BBI) isolated from plant seeds are small proteins active against trypsin and/or chymotrypsin. These inhibitors have been extensively studied in terms of their structure, interactions, function and evolution. Examination of the known three-dimensional structures of BBIs revealed similarities and subtle differences. The hydrophobic core, deduced from surface accessibility and hydrophobicity plots, corresponding to the two tandem structural domains of the double headed BBI are related by an almost exact two-fold, in contrast to the reactive site loops which depart appreciably from the two-fold symmetry. Also, the orientations of inhibitory loops in soybean and peanut inhibitors were different with respect to the rigid core. Based on the structure of Adzuki bean BBI-trypsin complex, models of trypsin and chymotryspin bound to the monomeric soybean BBI (SBI) were constructed. There were minor short contacts between the two enzymes bound to the inhibitor suggesting near independence of binding. Binding studies revealed that the inhibition of one enzyme in the presence of the other is associated with a minor negative cooperativity. In order to assess the functional significance of the reported oligomeric forms of BBI, binding of proteases to the crystallographic and non-crystallographic dimers as found in the crystal structure of peanut inhibitor were examined. It was found that all the active sites in these oligomers cannot simultaneously participate in inhibition.

Item Type: Article
Uncontrolled Keywords: Plant seed inhibitors; Bowman-Birk inhibitor; simultaneous inhibition; computer modelling.
Subjects: 500 Natural Sciences and Mathematics > 07 Life Sciences > 03 Biochemistry & Molecular Biology > 16 Protein Biochemistry
600 Technology > 08 Food technology > 22 Legumes-Pulses
Divisions: Dept. of Biochemistry
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 12 Jun 2015 10:35
Last Modified: 29 Nov 2016 10:19
URI: http://ir.cftri.com/id/eprint/11782

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