Heat-induced reversible gelation of arachin: kinetics, thermodynamics and protein species involved in the process.
Arachin forms a heat-reversible gel under certain experimental conditions. The minimal gelling concentration for this system is 7.25%. Above minimal gelling concentration calculation of thermodynamic parameters for gelation of arachin revealed a constant delta Hbonding (-1220 cal.mol-1) where delta Sbonding values varied with an increase in protein concentration (ranging from -4.01 e.u. at 7.5% to -3.48 e.u. at 10.0%). The main steps involved in the gelation phenomenon include thermal denaturation of arachin, partial aggregation of heat-denatured protein molecules, setting of protein solution and maturation of the gel formed. Gel maturation process follows first order kinetics and is characterized by a large positive delta G+(+) (22,030 cal.mol-1). Determination of delta H+(+) and delta S+(+) for this process revealed that mostly delta S+(+) (-62.9 e.u.) contributes to the large positive delta G+(+), thus decreasing the overall rate of gel maturation process. This large negative delta S+(+) value probably arises from a loss of entropy of protein molecules because of their increased involvement in gel network formation. The polymer gel network seems to be primarily contributed by a part of both arachin dodecameric and hexameric species.
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Protein Technology Discipline, Central Food Technological Research Institute, Mysore, India.
D010367:Arachis; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D005782:Gels; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010940:Plant Proteins; D014674:Plant Proteins, Dietary / Q000737:chemistry*; D011489:Protein Denaturation; D011506:Proteins / Q000378:metabolism*; D013816:Thermodynamics
D005782:Gels; D010940:Plant Proteins; D014674:Plant Proteins, Dietary; D011506:Proteins; C000102:Arachin