Heat capacity of solid proteins by thermal analysis
In a continuing effort to better understand the thermodynamic properties of proteins, solid state heat capacities of poly(amino acid)s of all 21 naturally occurring amino 4 copoly(amino acid)s and about 10 proteins have been analyzed by now using the Advanced Thermal Analysis System, ATHAS. The experimental measurements were performed with adiabatic and differential scanning calorimetry from 10 to about 450 K. The heat capacities of the samples in their pure, solid states are linked to an approximate vibrational spectrum by making use of known group vibrations and a set of parameters, {Theta}{sub 1} and {Theta}{sub 3}, of the Tarasov function for the skeletal vibrations. Good agreement is found between experiment and calculation with root mean square errors mostly within {+-}3%. The experimental data were analyzed also with an empirical addition scheme using data for the poly(amino acid)s. Based on this study, vibrational heat capacity can now be predicted for all proteins with an accuracy comparable to common experiments. Furthermore, gradual transitions, indicative of molecular motion prior to devitrification, melting, or decomposition, can be identified. The new experimental data compared here with the prior samples are: bovine {beta}-lactoglobulin, chicken lysozyme and ovalbumin.
- Research Organization:
- Oak Ridge National Lab., TN (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States); National Science Foundation, Washington, DC (United States)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 548902
- Report Number(s):
- ORNL/CP--95001; CONF-9709121--; ON: DE98001070; CNN: Grant DMR-973692
- Country of Publication:
- United States
- Language:
- English
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