Stereoselective hydration of (RS)-phenylglycine nitrile by new whole cell biocatalysts

✍ Scribed by Martina Hensel; Sabine Lutz-Wahl; Lutz Fischer

• Book ID: 104359556
• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 121 KB
• Volume: 13
• Category: Article
• ISSN: 0957-4166
• DOI: 10.1016/s0957-4166(02)00751-6

✦ Synopsis

Five new bacterial isolates with stereoselective nitrile hydratase activity against (RS)-2-phenylpropionitrile and (RS)-phenylglycine nitrile were investigated. The permeabilized whole cell isolates selectively hydrate the (S)-enantiomer of phenylglycine nitrile with E values of 1.2-5.4. One isolate, which was identified as Pantoea endophytica, produced pure (S)-phenylglycine (>99% ee) as a result of hydrolysis of (S)-phenylglycine amide by an (S)-specific amidase. Surprisingly, in the hydrolysis of (RS)-phenylglycine nitrile, it was found that the (R)-amide was accumulated in excess (21% ee) despite the nitrile hydratase produced by Pantoea endophytica was (S)-selective. The synthesis of pure (R)-phenylglycine (>99% ee) was achieved in time course studies using another Pantoea sp. with (R)-selective amidase. In the case of Nocardioides sp. the intermediate product, (S)-phenylglycine amide, could be produced (52% ee) without its subsequent hydrolysis into the acid due to the apparent absence of any amidase activity.