Stereoselective hydrogenation of olefins using rhodium-substituted carbonic anhydrase - A new reductase

Qing Jing, Krzysztof Okrasa, Romas J Kazlauskas

Research output: Contribution to journalArticlepeer-review

74 Scopus citations

Abstract

One useful synthetic reaction missing from nature's toolbox is the direct hydrogenation of substrates using hydrogen. Instead nature uses co-factors like NADH to reduce organic substrates, which adds complexity and cost to these reductions. To create an enzyme that can directly reduce organic substrates with hydrogen, researchers have combined metal hydrogénation catalysts with proteins. One approach is an indirect link where a ligand is linked to a protein and the metal binds to the ligand. Another approach is direct linking of the metal to protein, but nonspecific binding of the metal limits this approach. Herein, we report a direct hydrogenation of olefins catalyzed by rhodium(I) bound to carbonic anhydrase (CA-[Rh]). We minimized nonspecific binding of rhodium by replacing histidine residues on the protein surface using site-directed mutagenesis or by chemically modifying the histidine residues. Hydrogenation catalyzed by CA-[Rh] is slightly slower than for uncomplexed rhodium(I), but the protein environment induces stereoselectivity favoring cis- over transstilbene by about 20:1. This enzyme is the first cofactor-independent reductase that reduces organic molecules using hydrogen. This catalyst is a good starting point to create variants with tailored reactivity and selectivity. This strategy to insert transition metals in the active site of metalloenzymes opens opportunities to a wider range of enzyme-catalyzed reactions.

Original languageEnglish (US)
Pages (from-to)1370-1376
Number of pages7
JournalChemistry - A European Journal
Volume15
Issue number6
DOIs
StatePublished - Jan 26 2009

Keywords

  • Carbonic anhydrase
  • Enzyme catalysis
  • Hydrogenation
  • Metalloenzymes
  • Protein modifications

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