The contribution of two disulfide bonds in the trypsin binding domain of horsegram (Dolichos biflorus) Bowman-Birk inhibitor to thermal stability and functionality.

Vinod, Kumar and Lalitha, R. Gowda (2013) The contribution of two disulfide bonds in the trypsin binding domain of horsegram (Dolichos biflorus) Bowman-Birk inhibitor to thermal stability and functionality. Archives of Biochemistry and Biophysics, 537. pp. 49-61. ISSN 0003-9861

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Abstract

The major Bowman-Birk inhibitor (BBIs) of horsegram (Dolichos biflorus) HGI-III, contains seven interweaving disulfides and is extremely stable to high temperatures. The contributions of two disulfide bonds in the trypsin domain to thermal stability and functionality were evaluated using disulfide deletion variants of wild type protein. Thermal denaturation kinetics, differential scanning calorimetry and urea denaturation studies indicate that the absence of either of the two disulfides destabilizes the protein significantly. C20–C66 contributes substantially to both thermal stability and controls trypsin and chymotrypsin inhibitor activity. These two disulfides act in synergy as deletion of both disulfides leads to a complete loss of thermal stability. The data indicate that the two subdomains are not entirely independent of each other. Long range interactions, between the domains are facilitated by C20–C66. The deletion of the disulfide bonds also increased proteolytic susceptibility in a manner similar to the decreased thermal stability. From this study of rHGI a prototype of legume BBIs in can be concluded that among the array of seven evolutionarily conserved disulfide bonds, the disulfide C20–C66 that connects a residue in the trypsin domain with a residue at the border of the same domain plays a dominant role in maintaining functional and structural stability.

Item Type:	Article
Uncontrolled Keywords:	Trypsin inhibitor, Site directed mutagenesis Proteolytic stability, Orthogonal geometry, Differential scanning calorimetry
Subjects:	500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 29 Protein Chemistry 600 Technology > 08 Food technology > 22 Legumes-Pulses
Divisions:	Protein Chemistry and Technology
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	13 Nov 2013 04:03
Last Modified:	13 Nov 2013 04:03
URI:	http://ir.cftri.res.in/id/eprint/11278

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