초록
<P><B>Abstract</B></P><P>An endoglucanase from <I>Aspergillus fumigatus</I> ABK9 was purified from the culture extract of solid‐state fermentation and its some characteristics were evaluated. The molecular weight of the purified enzyme (56.3 kDa) was determined by sodium dodecyl sulfate–polyacrylamide gel electrophoresis, zymogram analysis and confirmed by MALDI‐TOF mass spectrometry. The enzyme was active optimally at 50 °C, pH 5.0 and stable over a broad range of pH (4.0–7.0) and NaCl concentration of 0–3.0 M. The p<I>K</I><SUB>a1</SUB> and p<I>K</I><SUB>a2</SUB> of the ionizable groups of the active sites were 2.94 and 6.53, respectively. The apparent <I>K</I><SUB>m</SUB>, <I>V</I><SUB>max</SUB>, and <I>K</I><SUB>cat</SUB> values for carboxymethyl cellulose were 6.7 mg ml<SUP>−1</SUP>, 775.4 µmol min<SUP>−1</SUP>, and 42.84 × 10<SUP>4</SUP> s<SUP>−1</SUP>, respectively. Thermostability of the enzyme was evidenced by the high activation energy (91.45 kJ mol<SUP>−1</SUP>), large enthalpy for activation of denaturation (88.77 kJ mol<SUP>−1</SUP>), longer half‐life (<I>T</I><SUB>1/2</SUB>) (433 min at 50 °C), higher melting temperature (<I>T</I><SUB>m</SUB>) (73.5 °C), and <I>Q</I><SUB>10</SUB> (1.3) values. All the characteristics favors its suitability as halotolerant and thermostable enzyme during bioprocessing of lignocellulosic materials.</P>