Heat capacity Solid amino acids

Tables 8.2 and 8.3 present molar heat capacities of solid amino acids and polyamino acids. Table 8.4 presents specific heat capacities of anhydrous and hydrated proteins. All of the measurements were done by using adiabatic absolute calorimetry and their accuracy is better than 1-2%. Heat capacity of anhydrous proteins can be predicted using empirical approach developed by Wunderlich (see e.g., [1]).

The measured heat capacity increment associated with the transfer of an apolar hydrogen from a crystalline amino acid solid into water is 6.7 0.3 cal K-1 mol-1 or 0.45 0.02 cal (mol A2)-1 of apolar surface (Murphy and Gill, 1990, 1991). This same value is observed for the transfer of 1-alkanols into water (Hall n et al., 1986). The same value is also observed for the transfer of liquid hydrocarbons into water (Gill and Wadso, 1976), and for the dissolution of alkane... 

Fig. 4. Temperature dependence of the specific enthalpy of denaturation of myoglobin and ribonuclease A (per mole of amino acid residues) in solutions with pH and buffer providing maximal stability of these proteins and compensation of heat effects of ionization (see Privalov and Khechinashvili, 1974). The broken extension of the solid lines represents a region that is less certain due to uncertainty in the A°CP function (see Fig. 2). The dot-and-dash lines represent the functions calculated with the assumption that the denaturation heat capacity increment is temperature independent.

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