Chemo-enzymatic synthesis of enantiomerically pure α-H and α-alkyl α-amino acids and derivatives. In: Lubec G, Rosenthal GA, editors. Amino Acids. Dordrecht: Springer Netherlands; 1990. pp. 119-25. [DOI: 10.1007/978-94-011-2262-7_14]

Purification and Characterization of an l -Amino Amidase from Mycobacterium neoaurum ATCC 25795

An l -amino amidase from Mycobacterium neoaurum ATCC 25795 responsible for the enantioselective resolution of dl -α-methyl valine amide was purified and characterized. The purification procedure included ammonium sulfate fractionation, gel filtration, and anion-exchange chromatography, which resulted in a homogeneous preparation of the enzyme with a native molecular mass of 136 kDa and a subunit molecular mass of 40 kDa. The purified enzyme displayed the highest activity at 50°C and at pH 8.0 and 9.5. The enzyme was strongly inhibited by the metal-chelating agent 1,10-phenanthroline, the disulfide-reducing agent dithiothreitol, and the cysteine proteinase inhibitor iodoacetamide. The purified amino amidase showed a unique l -enantioselective activity towards a broad range of both α-H- and α-alkyl-substituted amino acid amides, with the highest activity towards the cyclic amino acid amide dl -proline amide. No activity was measured with dl -mandelic acid amide nor with the dipeptide l -phenylalanine- l -leucine. The highest catalytic efficiency ( k cat / K m ratio) was measured with dl -α-allyl alanine amide, dl -α-methyl phenylalanine amide, and dl -α-methyl leucine amide.