Conversion of aliphatic nitriles by the arylacetonitrilase from Pseudomonas fluorescens EBC191.
The conversion of aliphatic nitriles by the arylacetonitrilase from Pseudomonas fluorescens EBC191 (NitA) was analyzed. The nitrilase hydrolysed a wide range of aliphatic mono- and dinitriles and showed a preference for unsaturated aliphatic substrates containing 5-6 carbon atoms. In addition, increased reaction rates were also found for aliphatic nitriles carrying electron withdrawing substituents (e.g. chloro- or hydroxy-groups) close to the nitrile group. Aliphatic dinitriles were attacked only at one of the nitrile groups and with most of the tested dinitriles the monocarboxylates were detected as major products. In contrast, fumarodinitrile was converted to the monocarboxylate and the monocarboxamide in a ratio of about 65:35. Significantly different relative amounts of the two products were observed with two nitrilase variants with altered reaction specifities. NitA converted some aliphatic substrates with higher rates than 2-phenylpropionitrile, which is one of the standard substrates for arylacetonitrilases. This indicated that the traditional classification of nitrilases as "arylacetonitrilases", "aromatic" or "aliphatic" nitrilases might require some corrections. This was also suggested by the construction of some variants of NitA which were modified in an amino acid residue which was previously suggested to be essential for the conversion of aliphatic substrates by a homologous nitrilase.
['Brunner|Siegfried|S|', 'Eppinger|Erik|E|', 'Fischer|Stefanie|S|', 'Gröning|Janosch|J|', 'Stolz|Andreas|A|http://orcid.org/0000-0002-8009-0178']
D000097:Acetonitriles D000619:Aminohydrolases D000641:Ammonia D020134:Catalytic Domain D005227:Fatty Acids D006868:Hydrolysis D008958:Models, Molecular D016297:Mutagenesis, Site-Directed D009570:Nitriles D011551:Pseudomonas fluorescens D013379:Substrate Specificity
Nitrilase Biotransformation Regioselective hydrolysis Substrate specifity