초록
<P><B>Abstract</B></P> <P>The final step in lignocellulose enzymatic saccharification is the cellobiose conversion to glucose by β-glucosidases (BG). In this work, a valid kinetic model to describe cellobiose degradation for an industrial mixture of BG enzymes present in <I>Aspergillus fumigatus</I> is selected. Firstly, the enzyme mixture was characterised in terms of protein content and enzymatic activity on p-NPG (1326UmL<SUB>preparation</SUB> <SUP>−1</SUP>), determining the molecular weight of the only BG activity band observed in zymograms by SDS-PAGE and MALDI-TOF: 94kDa. Subsequently, to select the correct kinetic model for the enzymatic hydrolysis of cellobiose, a combined strategy was performed: Firstly, non-linear regressions were applied to initial hydrolysis rate data for different enzyme concentrations and initial substrate and product concentrations, observing inhibition by cellobiose and glucose. Secondly, the optimal kinetic model was discriminated by a coupled non-linear regression-DOE numerical integration approach, by fitting several possible kinetic models involving different product inhibition mechanisms to progress curve data from runs at various initial substrate concentrations and temperatures. The best kinetic model involves non-competitive substrate inhibition and product competitive inhibition with two binding sites for glucose.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Phenomenological kinetics for cellobiose hydrolysis by a β-glucosidase from <I>Aspergillus fumigatus</I> were analyzed. </LI> <LI> Enzyme mixture was characterized in terms of activity, protein content and molecular weight. </LI> <LI> Reaction rate and Progress curve methodologies were employed. </LI> <LI> Effects of temperature, and enzyme, product and substrate concentration on reaction rate were assessed. </LI> <LI> Physical and statistical discrimination advocates for an MM complex inhibition model. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>