Structure‐Based Mechanism of Oleate Hydratase from Elizabethkingia meningoseptica

Hydratases provide access to secondary and tertiary alcohols by regio‐ and/or stereospecifically adding water to carbon‐carbon double bonds. Thereby, hydroxy groups are introduced without the need for costly cofactor recycling, and that makes this approach highly interesting on an industrial scale. Here we present the first crystal structure of a recombinant oleate hydratase originating from Elizabethkingia meningoseptica in the presence of flavin adenine dinucleotide (FAD). A structure‐based mutagenesis study targeting active site residues identified E122 and Y241 as crucial for the activation of a water molecule and for protonation of the double bond, respectively. Moreover, we also observed that two‐electron reduction of FAD results in a sevenfold increase in the substrate hydration rate. We propose the first reaction mechanism for this enzyme class that explains the requirement for the flavin cofactor and the involvement of conserved amino acid residues in this regio‐ and stereoselective hydration.     

Stochastic web-based natural language dialog planning for web information filtering

This work addresses natural language dialog planning for an intelligent web filtering model, which lets the user filter search results obtained by a traditional search engine and assists them to find what they really are looking for. Unlike state-of-the-art approaches, a stochastic planning model is proposed for a web-driven dialog system which uses Conditional Random Fields to predict next dialog moves. Experiments with real web users and different interaction settings show the promise of the approach to web-based adaptive planning aimed at information filtering.