Two-parameter kinetic model based on a time-dependent activity coefficient accurately describes enzymatic cellulose...

Area of Science:

• Biotechnology
• Biochemical Engineering
• Renewable Energy

Background:

• Lignocellulosic biomass offers a sustainable source for low-carbon liquid fuels.
• Biomass recalcitrance and high enzyme costs hinder cellulosic fuel production.
• Existing kinetic models struggle with the heterogeneous nature of cellulose and lack of steady state.

Purpose of the Study:

• To develop a robust kinetic model for enzymatic cellulose digestion.
• To provide a framework for understanding cellulase activity and substrate recalcitrance.
• To enable mechanistic studies and comparisons of cellulases from different sources.

Main Methods:

• Developed a two-parameter kinetic model based on Michaelis-Menten kinetics.
• Incorporated a time-dependent activity coefficient analogous to fractal-like kinetics.
• Validated the model using enzymes from *Thermobifida fusca* and *Trichoderma reesei*.

Main Results:

• The model successfully describes enzymatic cellulose digestion kinetics.
• Identified two key parameters: total activity coefficient and an intrinsic recalcitrance constant.
• Demonstrated applicability to individual cellulases, mixtures, and crude enzyme preparations.

Conclusions:

• The new model offers a simplified yet mechanistically relevant approach to studying enzymatic cellulose digestion.
• The model's parameters provide insights into cellulase efficiency and substrate interactions.
• This approach is potentially applicable to other enzyme systems with heterogeneous substrates and non-steady-state conditions.