Chemical Modification of α-amylase from Locale Bacteria Isolate Bacillus subtilis ITBCCB148 with Glyoxylic Acid YANDRI*, NINA ANGGRAINI, TATI SUHARTATI and SUTOPO HADI

Chemical modification of α-amylase from locale bacteria isolate Bacillus subtilis ITBCCB148 using glyoxylic acid to increase thermal stability of the enzyme has successfully been done. The results showed that the native and the modified enzyme have similar pH of 6.0 and optimum temperature of 60°C. However, the thermal stability of the modified enzymes was increased 1.8-2.1 times compared to the native enzyme. The thermal stability data obtained at 60°C for 60 minutes as following: the native enzyme has residual activity 17% and half-life (t 1/2 ) = 25.3 min., while the modified enzymes with modification degree of 67, 69 and 82% have residual activity of 39, 44 and 47%, respectively and t 1/2 of 46.2, 53.3 and 49.5 minutes, respectively.