title: Enzyme toolbox: novel enantiocomplementary imine reductases.
abstract: Reducing reactions are among the most useful transformations for the generation of chiral compounds in the fine-chemical industry. Because of their exquisite selectivities, enzymatic approaches have emerged as the method of choice for the reduction of C=O and activated C=C bonds. However, stereoselective enzymatic reduction of C=N bonds is still in its infancy-it was only recently described after the discovery of enzymes capable of imine reduction. In our work, we increased the spectrum of imine-reducing enzymes by database analysis. By combining the currently available knowledge about the function of imine reductases with the experimentally uncharacterized diversity stored in protein sequence databases, three novel imine reductases with complementary enantiopreference were identified along with amino acids important for catalysis. Furthermore, their reducing capability was demonstrated by the reduction of the pharmaceutically relevant prochiral imine 2-methylpyrroline. These novel enzymes exhibited comparable to higher catalytic efficiencies than previously described enzymes, and their biosynthetic potential is highlighted by the full conversion of 2-methylpyrroline in whole cells with excellent selectivities.
authors.affiliation: Institute of Technical Biochemistry, University of Stuttgart, Allmandring 31, 70569 Stuttgart (Germany).
authors.forename: Philipp N
authors.initials: PN
authors.lastname: Scheller
authors.forename: Silvia
authors.initials: S
authors.lastname: Fademrecht
authors.forename: Sebastian
authors.initials: S
authors.lastname: Hofelzer
authors.forename: Jürgen
authors.initials: J
authors.lastname: Pleiss
authors.forename: Friedemann
authors.initials: F
authors.lastname: Leipold
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Turner
authors.forename: Bettina M
authors.initials: BM
authors.lastname: Nestl
authors.forename: Bernhard
authors.initials: B
authors.lastname: Hauer
mesh_terms: D055162:Biocatalysis; D007097:Imines / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D015394:Molecular Structure; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D011759:Pyrrolidines / Q000737:chemistry / Q000378:metabolism; D013237:Stereoisomerism
chemical_list: D007097:Imines; D011759:Pyrrolidines; D010088:Oxidoreductases
keywords: asymmetric catalysis; biocatalysis; database analysis; enantiopure amine; imine reductase