Modeling the activity burst in the initial phase of cellulose hydrolysis by the processive cellobiohydrolase Cel7A

Zdenek Petrášek, Manuel Eibinger, Bernd Nidetzky*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

The hydrolysis of cellulose by processive cellulases, such as exocellulase TrCel7A from Trichoderma reesei, is typically characterized by an initial burst of high activity followed by a slowdown, often leading to incomplete hydrolysis of the substrate. The origins of these limitations to cellulose hydrolysis are not yet fully understood. Here, we propose a new model for the initial phase of cellulose hydrolysis by processive cellulases, incorporating a bound but inactive enzyme state. The model, based on ordinary differential equations, accurately reproduces the activity burst and the subsequent slowdown of the cellulose hydrolysis and describes the experimental data equally well or better than the previously suggested model. We also derive steady-state expressions that can be used to describe the pseudo-steady state reached after the initial activity burst. Importantly, we show that the new model predicts the existence of an optimal enzyme-substrate affinity at which the pseudo-steady state hydrolysis rate is maximized. The model further allows the calculation of glucose production rate from the first cut in the processive run and reproduces the second activity burst commonly observed upon new enzyme addition. These results are expected to be applicable also to other processive enzymes.

Original languageEnglish
JournalBiotechnology and Bioengineering
Early online date4 Dec 2018
DOIs
Publication statusE-pub ahead of print - 4 Dec 2018

Keywords

  • activity burst
  • cellobiohydrolase
  • cellulose
  • hydrolysis
  • modeling
  • processive action

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology

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