Bridging the bridge - Stabilization of CalB against H2H2 and its application in epoxidation reactions

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

Abstract

tChemo-enzymatic reactions combine the advantages of chemistry and biocatalysis. Chemical synthesisprovides precursor molecules and low costs, whereas the application of enzymes provides selectivity.Additionally, the mild reaction conditions of enzymatic approaches allow the chemical application ofintermediates and/or products that otherwise are not accessible. One example is the in situ production ofperoxycarboxylic acids (peracids) by Candida antarctica lipase B (CalB). In contrast to the harsh conditions of chemical peracid synthesis, CalB catalyzed reactions run at low temperatures and without additives.Unfortunately, the enzyme is rapidly inactivated by the oxidative environment. Herein, we report on CalBstabilization by preventing disulfide cleavage after H2O2exposure. Therefore, a bismaleimide function-alized linker was used to convert all the enzyme’s disulfide bridges to more stable thioether linkages.These bonds are still affected by hydrogen peroxide but will not open upon oxidation. A two- to four-fold excess of this linker was optimal to avoid enzyme oligomerization. At the same time, a 1.5 foldincrease in half life time after exposure to hydrogen peroxide was achieved. To our knowledge, such anapproach to intramolecular disulfide stabilization has never been reported before, but might be a generalstrategy for enzyme engineering. Furthermore, a carrier screening was performed, identifying differentoptimal carrier types for CalB immobilization. The combination of stabilization by disulfide conjugationand immobilization was expanded by the adoption of a thermostabilized double mutant. Finally, chemo-enzymatic epoxidations of alkenes were examined in batch experiments and under continuous processconditions. Activity loss was reduced by 50% and a 75% increase in long-term stability was achieved incomparison to the commercial preparation.

Details

Original languageEnglish
Pages (from-to)S179-S187
JournalJournal of Molecular Catalysis B: Enzymatic
Volume2016
Issue number133
Publication statusPublished - 2016
Peer-reviewedYes

External IDs

ORCID /0000-0002-2912-546X/work/171551946

Keywords

Keywords

  • Lipase, hydrogen peroxide, epoxidation