The Chemical Modification of Cellulase Obtained from Bacillus Subtilis Itbccb148 with Dimethyladimipidate

Yandri, Putri Amalia, Tati Suhartati, and Sutopo Hadi

Department of Chemistry, University of Lampung Jl. S. Brojonegoro No. 1 Gedongmeneng Bandar Lampung 35145

DOI : http://dx.doi.org/10.13005/bbra/1877

ABSTRACT: Cellulase obtained from Bacillus subtilis ITBCCB148 has successfully been isolated and purified. The native enzyme was modified with dimethyladipimidate (DMA) to increase the stability of the enzyme. The native and modified enzymes were characterized including determination of optimum temperature, optimum pH and thermal stability. The activity of the cellulase was determined based on Mendels method and the protein content was determined based on Lowry method. The results showed that the native enzyme has optimum temperature of 55^oC and optimum pH of 5.5. The thermal stability for 60 minutes at temperature of 55^oC indicated that the native enzyme has k_i  = 0.034 min.t^-1, t_1/2 = 20.4 min., and ΔG_i = 100.9 kJ/mol.  The modified enzyme with modification degrees of 64.5; 69.5 and 82% have optimum temperature of 55 ^oC and optimum pH of 6.  The thermal stability for 60 minutes at temperature of 55^oC of the modified enzyme with modification degrees of 64.5; 69.5 and 82% have k_i values of 0.024; 0.021 and 0.022 min.^-1, t_1/2 values of  28.9; 33.0 and 31.5 minutes, and ΔG_i values of  101.9; 102.3 and 102.2 kJ/mol, respectively.  The modification with DMA has successfully increased the thermal stability of the modified enzymes between 1.4 – 1.6 times compared to that of the native enzyme. The decrease of ki values, increase of half-lives and  ΔG_i indicated that the modified enzymes were more stable compared to the native enzyme.

KEYWORDS: cellulase; Bacillus subtilis ITBCCB148; dimethyladimipidate

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