Kinetics and thermodynamics of the mechanism of interaction of sodium phytate with alpha-globulin.

Rajendran, S. and Prakash, V. (1993) Kinetics and thermodynamics of the mechanism of interaction of sodium phytate with alpha-globulin. Biochemistry, 32 (13). pp. 3474-8. ISSN 0006-2960

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Abstract

The precipitation mechanism of alpha-globulin in the presence of myo-inositol hexaphosphate (sodium phytate) was studied in detail. The maximum interaction was found at pH 2.3 where the protein was in a dissociated state having an 8.3S aggregate and a 1.5S monomer. This interaction was predominantly dependent upon the sodium phytate to protein ratio. Velocity sedimentation studies indicated polymer formation due to preferential progressive binding of ligand to polymer, whose size and concentration increased with an increase in sodium phytate concentration. The polymer formation was shown to be ligand mediated and exists independently in solution along with the monomer. The binding isotherm by equilibrium dialysis confirmed differential binding of sodium phytate to the polymer and the monomer as indicated by two sets of binding sites, one having 7 +/- 2 sites of a K value 1.3 x 10(-4) mol-1 and the other having 56 +/- 3 sites with a K value of 2.8 x 10(-3) mol-1. Binding resulted in perturbation of chromophores of protein due to charge effects. The kinetics of the polymer formation was shown to be a pseudo-first-order reaction having two steps. The initial fast reaction involving conformational changes has rate constants of k1 = 52.4 x 10(-3) s-1 and k' = 67.5 x 10(-3) s-1, followed by a slow reaction step of rate constants k2 = 4.3 x 10(-3) s-1 and k'2 = 2.9 x 10(-3) s-1 at sodium phytate concentrations of 1 x 10(-4) M and 5 x 10(-4) M, respectively.

Item Type:	Article
Uncontrolled Keywords:	alpha-Globulin, sesame seed, precipitation mechanism
Subjects:	600 Technology > 08 Food technology > 16 Nutritive value > 03 Proteins 600 Technology > 08 Food technology > 19 Lipids-oils/fats > 01 Oilseeds
Divisions:	Protein Chemistry and Technology
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	09 Apr 2018 05:17
Last Modified:	09 Apr 2018 05:17
URI:	http://ir.cftri.res.in/id/eprint/2290

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