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A novel enzymatic production system of optically pure β-hydroxy α-amino acids was developed. Two enzymes were used for the system: an N-succinyl L-amino acid β-hydroxylase (SadA) belonging to the iron(II)/α-ketoglutarate-dependent dioxygenase superfamily and an N-succinyl L-amino acid desuccinylase (LasA). The genes encoding the two enzymes are part of a gene set responsible for the biosynthesis of peptidyl compounds found in the Burkholderia ambifaria AMMD genome. SadA stereoselectively hydroxylated several N-succinyl aliphatic L-amino acids and produced N-succinyl β-hydroxy L-amino acids, such as N-succinyl- L-β-hydroxyvaline, N-succinyl- L-threonine, (2 S,3 R)- N-succinyl- L-β-hydroxyisoleucine, and N-succinyl- L- threo-β-hydroxyleucine. LasA catalyzed the desuccinylation of various N-succinyl- L-amino acids. Surprisingly, LasA is the first amide bond-forming enzyme belonging to the amidohydrolase superfamily, and has succinylation activity towards the amino group of L-leucine. By combining SadA and LasA in a preparative scale production using N-succinyl- L-leucine as substrate, 2.3 mmol of L- threo-β-hydroxyleucine were successfully produced with 93% conversion and over 99% of diastereomeric excess. Consequently, the new production system described in this study has advantages in optical purity and reaction efficiency for application in the mass production of several β-hydroxy α-amino acids. [ABSTRACT FROM AUTHOR]

The front cover picture, provided by Makoto Hibi, Jun Ogawa et al., depicts Fe(II)/α ‐ ketoglutarate (αKG) ‐ dependent dioxygenases, which are hydroxylation biocatalysts catalyzing highly selective monooxygenation available to industrial applications. Recently, a great number of Fe(II)/αKG ‐ dependent dioxygenases with a variety of functions has been found in the genome database, and collected into a biocatalyst library. One of these enzymes, N ‐ succinyl L ‐ amino acid β ‐ hydroxylase, was applied to an enzymatic cascade system together with N ‐ succinyl L ‐ amino acid desuccinylase for the production of optically pure β ‐ hydroxy α ‐ amino acids. Details can be found in the full paper on pages 767 – 774 (M. Hibi, T. Kasahara, T. Kawashima, H. Yajima, S. Kozono, S. V. Smirnov, T. Kodera, M. Sugiyama, S. Shimizu, K. Yokozeki, and J. Ogawa, Adv. Synth. Catal. 2015, 357, 767 – 774; DOI: 10.1002/adsc.201400672). [ABSTRACT FROM AUTHOR]

• Mixing CSS to molasses did not deteriorate ethanol production. • CSS + molasses mixed medium resulted in ∼27 % lower COD of spent wash. • Resulting spent wash suited biological treatment due to higher BOD/COD ratio. • CSS can be supplemental substrate to molasses-based ethanol production. Cellulosic sugar syrup (CSS), as a potential substrate to many biochemical industries, has been integrated into molasses-based ethanol production. It is seen as an additional substrate to alleviate the shortage of molasses supply. The impact of the CSS integration was assessed in terms of ethanol production and the quality of spent wash obtained after ethanol distillation. In this study, 0.02% (w/v) of urea was supplemented into molasses, as it is the minimum amount that provided high ethanol concentration and fermentation efficiency. Integrating CSS to molasses up to 28.5% (w/v) did not deteriorate the ethanol production nor fermentation efficiency. It also reduces the chemical oxygen demand (COD) of the spent wash by 24% when integrating at least 15% (w/v) of CSS to molasses, comparing to the value of the spent wash from molasses medium. The biodegradability of the spent wash also increased as compared to that of molasses medium. [ABSTRACT FROM AUTHOR]

A novel dioxygenase from Burkholderia ambifaria AMMD (SadA) stereoselectively catalyzes the C3-hydroxylation of N-substituted branched-chain or aromatic L-amino acids, especially N-succinyl-L-leucine, coupled with the conversion of α-ketoglutarate to succinate and CO2. To elucidate the structural basis of the substrate specificity and stereoselective hydroxylation, we determined the crystal structures of the SadA.Zn(II) and SadA.Zn(II).α-KG complexes at 1.77 Å and 1.98 Å resolutions, respectively. SadA adopted a double-stranded β-helix fold at the core of the structure. In addition, an HXD/EXnH motif in the active site coordinated a Zn(II) as a substitute for Fe(II). The α-KG molecule also coordinated Zn(II) in a bidentate manner via its 1-carboxylate and 2-oxo groups. Based on the SadA.Zn(II).α-KG structure and mutation analyses, we constructed substrate-binding models with N-succinyl-L-leucine and N-succinyl-L-phenylalanine, which provided new insight into the substrate specificity. The results will be useful for the rational design of SadA variants aimed at the recognition of various N-succinyl L-amino acids. [ABSTRACT FROM AUTHOR]