The structure of a P450 ω‐hydroxylase bound to its fatty acid product was determined, which revealed a narrow substrate tunnel that leads to the heme. The introduction of an arginine side chain in proximity to the carboxyl group of the fatty acid led to a reduced KM value for dodecanoic acid, which suggests the importance of an anchoring point in the active site. An increase in the flexibility of the substrate recognition region was also engineered, which resulted in a threefold improved product formation.

The front cover artwork for Issue 20/2016 is provided by researchers from the Universität Stuttgart (Germany) and the University of York (United Kingdom). The image shows a free fatty acid substrate which drops into the active site of a P450 enzyme in an aqueous solution. The fatty acid is kept in the splash through the specific structural elements of the enzyme. See the Full Paper itself at http://dx.doi.org/10.1002/cctc.201600680.

The interconversion of non-activated alkenes and alcohols, catalysed by (de)hydratases, has great potential in biotechnology for the generation of fine and bulk chemicals. LinD is a cofactor-independent enzyme that catalyses the reversible (de)hydration of the tertiary alcohol (S)-linalool to the triene b-myrcene, and also its isomerization to the primary alcohol geraniol. Structure-informed mutagenesis of LinD, followed by activity studies, confirmed essential roles for residues C171, C180 and H129 in water activation for the hydration of b-myrcene to linalool. However, no evidence of covalent thioterpene intermediates was found using either X-ray crystallography, mass spectrometry, or QM/MM nudged elastic band simulations. Labelling and NMR experiments confirmed a role for residue D39 in (de)protonation of the linalool carbon C10 in the isomerization of linalool to geraniol and also the intermediacy of b-myrcene in this isomerization reaction. X-ray, molecular dynamics and activity studies also suggested a significant role in catalysis for a mobile methionine residue M125, which exists in substantially altered orientations in different mutant structures.

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