Cavity size engineering of a beta-barrel protein generates efficient biohybrid catalysts for olefin metathesis

14/03/2018
 

Congratulations to Daniel Sauer and Alexander Grimm on another highlight publication!

Photo of Alexander Grimm and Daniel Sauer Copyright: Bio VI

The successful application of the presented cavity size engineering strategy to biohybrid catalysis can potentially be transferred to other beta-barrel protein scaffolds to generate cavity sizes that match the sterical demands of synthetic catalysts.

 
  Directed Evolution of NB4 Copyright: Bio VI

By incorporating a synthetic metal catalyst into a protein scaffold, a biohybrid catalyst is obtained. The protein scaffold can potentially alter the selectivity of the metal catalyst.and solubilizes it in water, while retaining their broad reaction scope. What’s new about this work is that until now, protein scaffolds for synthetic catalysts have mainly been engineered by exchanging individual amino acids. While a lot has been achieved using this conventional strategy, it is limited by the number of amino acids in the protein available for substitution.

 
  Olefin metathesis with NB4 Copyright: ACS Publications Comparison of conversion of cavity size engineered biohybrid catalyst and protein-free catalyst in ring opening metathesis polymerization.

Here, cavity size engineering of the beta-barrel protein nitrobindin was performed by duplicating multiple beta-strands to generate an expanded variant. It is the first time this has been done for biohybrid catalysis. By duplicating entire beta-strands, it was possible to covalently incorporate bulky catalysts and achieve excellent conversions in a whole series of olefin metathesis reactions – carbon-carbon double bond formation reactions. What is exciting about this is that the design strategy that was used can potentially be transferred to other beta-barrel protein scaffolds to generate cavity sizes that match the sterical demands of synthetic catalysts.

 
 

If high-throughput screening is applied to these new variants in the future, it should be possible to explore directed biohybrid catalyst evolution much more efficiently, which will likely further increase performance. This work was made possible through funding from the Deutsche Forschungsgemeinschaft and Bundesministerium für Bildung und Forschung.

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Grimm, A.R.*, Sauer, D.F.*, Davari, M.D., Zhu, L., Bocola, M., Kato, S., Onoda, A., Hayashi, T., Okuda, J., Schwaneberg, U. (2018). Cavity size engineering of a beta-barrel protein generates efficient biohybrid catalysts for olefin metathesis. ACS Catal., first published online Feb 28 DOI: 10.1021/acscatal.7b03652. *shared first authorship