Chemists continue to make great strides in raising the efficiency of inorganic catalysts that split water into hydrogen and oxygen. Of course, cyanobacteria have been busily carrying out more or less that same reaction for billions of years. Köninger et al. enlist their help in order to cleanly source hydrogen equivalents (protons and electrons) for the reduction of carbon-carbon double bonds in enones. The authors introduce an enoate reductase enzyme to catalyze the formal hydrogenation with high enantioselectivity and photosynthetically derived oxygen as the sole by-product.
Angew. Chem. Int. Ed. 10.1002/anie.201601200 (2016).