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This study was undertaken to determine thermodynamic characteristics of B. subtilis p-4 and B. licheniformis p-5 proteases isolated from fermented anchovy paste. K_m values of two proteases for casein as a substrate were 0.38mM in p-4 protease and 0.18mM in p-5 protease, respectively. Denaturation constants(K_0) of p-4 and p-5 proteases were 12.2 × 10^(-5)/sec and 19.0 × 10^(-5)/sec at 40℃, and 35.7 × 10^(-5)/sec and 46.3 × 10^(-5)/sec at 50℃, respectively. Activation energies(E_a) of p-4 and p-5 proteases were 19.6 K㎈/㏖e and 15.2K㎈/㏖e, respectively. Free energy of activation(ΔG^≠), activation enthalpy(ΔH^≠) and activation entropy(ΔS^≠) at 40℃ were 23.21Kcal/ mole, 18.98K㎈/㏖e and -13.50 eu, respectively for p-4 protease and 22.93K㎈/㏖e, 14.58K㎈/㏖e and -26.68 eu, respectively for p-5 protease. The major amino acids in p-4 protease(151 residues of amino acid) were Gly, Glu, Pro, Asp, Ser, Ala, Lys and Leu, while those in p-5 protease (247 residues of amino acid) were Gly, Glu, Asp, Ala and Leu. It may be concluded that heat denaturation of two proteases showed liner regression curve and p-5 protease was more sensitive to hit than p-4 protease.
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