Effect of polyols on thermostability of xylanase from a tropical isolate of Aureobasidium pullulans and its application in prebleaching of rice straw pulp

SpringerPlus

Table 4 Thermodynamic parameters for the irreversible thermal inactivation of the purified xylanase from A. pullulans CBS 135684 cultivated in basal medium containing 1% (w/v) corncob

Temperature (°C)	k_d(min^-1)	t_1/2(min)	D_t(min)	ΔH^o(kJ.mol^-1)	ΔG^o(kJ.mol^-1)	ΔS^o(J.mol^-1.K^-1)
50	0.003	231	768	83.450	105.960	-0.070
55	0.004	173	576	83.400	106.850	-0.071
60	0.006	116	384	83.360	107.400	-0.072
65	0.012	58	192	83.320	107.100	-0.070
70	0.018	39	128	83.280	107.570	-0.071

The data were calculated from residual activity at different temperatures. The enzyme activity was assayed at 70°C for 30 min with 1% (w/v) beech wood xylan in 50 mM acetate buffer (pH 6.0).
Experiments were performed in triplicate (N = 3). E_d = 86.13 kJ.mol^-1, ΔH^o = Variations in enthalpy; ΔG^o = Variations in free energy; ΔS^o = Variations in entropy in free energy and ΔS^o = Variations in entropy.