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

Prakash, Balaji and Murthy, MRN and Sreerama, YN and Rajagopal Rao, D and Gowda, Lalitha R (1997) Studies on simultaneous nhibition of trypsin and chymotrypsin by horsegram Bowman-Birk inhibitor. In: Journal of Biosciences, 22 (5). pp. 545-554.

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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: Journal Article
Publication: Journal of Biosciences
Publisher: Springer
Additional Information: Copyright of this article belongs to Springer
Keywords: Plant seed inhibitors; Bowman-Birk inhibitor; simultaneous inhibition; computer modelling.
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 30 Nov 2010 07:15
Last Modified: 30 Nov 2010 07:15
URI: http://eprints.iisc.ac.in/id/eprint/34064

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