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Characterization of Pea Vicilin. 2. Consequences of Compositional Heterogeneity on Heat-Induced Gelation Behavior

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Author: O'Kane, F.E. · Happe, R.P. · Vereijken, J.M. · Gruppen, H. · Boekel, M.A.J.S. van
Type:article
Date:2004
Institution: TNO Voeding Centraal Instituut voor Voedingsonderzoek TNO
Source:Journal of Agricultural and Food Chemistry, 10, 52, 3149-3154
Identifier: 237769
doi: doi:10.1021/jf035105a
Keywords: Nutrition · Food technology · Aggregation · Gelation · Heterogeneity · N-terminal extension region · Pisum · Storage proteins · Turbid and transparent gels · vicilin · Alpha chain · Amino terminal sequence · Concentration response · Gelation · Heat · Hydrophobicity · Nonhuman · Pea · PH · Protein analysis · Protein folding · Turbidity · Gels · Heat · Hydrogen-Ion Concentration · Peas · Plant Proteins · Protein Folding · Sodium Chloride · Pisum · Pisum sativum

Abstract

The gelling characteristics of two vicilin fractions from pea (Pisum sativum L.) were compared over a range of pH and salt conditions after preliminary results showed that despite having equal opportunity to unfold, and expose hydrophobic residues, they had different minimum gelling concentrations (at pH 7.6). Furthermore, at this pH one fraction formed turbid gels and the other formed transparent gels. The fraction that formed transparent gels contained a substantial amount of the 70 kDa α-subunits of vicilin, and thus it was hypothesized that the highly charged N-terminal extension region on these 70 kDa subunits hinders gelation of this vicilin fraction at pH 7.6 and I = 0.2 due to repulsion of the net negative charge. The experiments designed to test this hypothesis are presented and discussed in this paper and prove that the hypothesis was true, which offers the possibility to control or modify the gelation behavior of vicilin on the basis of information of its subunit composition.