High-sensitivity modulation differential scanning calorimetry of protein denaturation
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Method of high-sensitivity modulation differential scanning calorimetry was applied for investigation of the kinetically controlled irreversible thermal denaturation of the trypsin inhibitor from soybeans (Kunitz inhibitor, KI) in diluted solution. The measurements were carried out with a temperature-modulation capillary nanocalorimeter designed and produced by the Institute of Biological Instrumentation of the RAS (Pushchino, Russia). An algorithm of the experimental data processing and corresponding software were developed. It was shown that the modulation nanocalorimetry allows one to obtain in one experiment the temperature dependence of the rate constant for irreversible protein denaturation. The temperature dependence of the rate constant and the activation energy of the irreversible denaturation of Kunitz inhibitor were determined. The obtained value of the activation energy (E a = 206 ± 6 kJ mol−1) agrees with independent estimates of this kinetic parameter.
KeywordsKunitz soybean trypsin inhibitor Thermal denaturation Kinetics Activation energy Lumry–Eyring model Temperature-modulation differential scanning nanocalorimetry
This research was supported by the Russian Foundation for Basic Researches (Grant 10-08-00063a).
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