Abstract

Yandri*, Eka Sulis Sundari, Tati Suhartati and Sutopo Hadi*

Chemical modification of α-amylase from locale bacteria isolate Bacillus subtilis ITBCCB148 using citraconic anhydride has been performed. increase thermal stability of the enzyme has successfully been done. The results showed that the modified enzymes with citraconic anhydride with modification degree of 45, 73, 82, 83, and 88% have similar optimum pH of 5.5 and optimum temperature of 60°C; ki of 0.030; 0.026; 0.024; 0.021 and 0.018 min-1, respectively; half-life (t1/2) of 23, 27, 29, 33 and 39 minutes, respectively; and ÄGi (in kJ/mol) of 102.91; 103.31; 103.53; 103.9 and 104.33, respectively. The result also showed that the chemical modification on locale bacteria isolate B. subtilis ITBCCB148 using citraconic anhydride has increased the thermal stability of the modified enzymes up to 2-3 times compared to the native enzyme.

α-amylase; chemical modification; citraconic anhydride; B. subtilis ITBCCB148

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