Abstract
In silico analysis of amino acid sequences of some aromatic and aliphatic microbial nitrilases for certain physiochemical properties and specificity to aromatic or aliphatic nitriles has been done. The multiple sequence alignment analysis of amino acid sequences has shown clear differences between aromatic and aliphatic nitrilases in terms of position specific presence of conserved amino acid. Statistical analysis of most of the physiochemical parameters did not show any clear distinction between the two nitrilases. In aromatic nitrilases the conserved amino acid residues besides active site domain triad (Glu, Lys, Cys) were His-129, Asn-168 and Arg-174 and these were replaced by Arg-129, His -168 and Lys-174 in aliphatic nitrilases. The physiochemical properties of these two groups of nitrilases also differed e.g. as compared to aliphatic nitrilases, aromatic nitrilases have lesser number of amino acid residues, lower molecular mass, higher pI values, higher content of Ala and Cys residues.
Highlights
Nitrilase was the first nitrile metabolizing enzyme reported almost four decades back that converts indole -3- acetonitrile to indole-3-acetic acid in plants (Thimann and Mahadevan, 1964)
Initial investigations suggested that nitrilases were specific for aromatic nitriles while nitrile hydratases had affinity for aliphatic nitriles but this distinction has to be reconsidered in the light of rapidly growing information on nitrile degrading enzymes
We report some physiochemical properties of aliphatic and aromatic nitrilases deduced from the in silico analysis of their amino acid sequences and the analysis of multiple sequence alignment of some microbial nitrilases which shows that specific type of amino acid at specific positions near the catalytic site are crucial to confer aromaticity or aliphaticity to a nitrilase
Summary
Nitrilase was the first nitrile metabolizing enzyme reported almost four decades back that converts indole -3- acetonitrile to indole-3-acetic acid (an auxin) in plants (Thimann and Mahadevan, 1964). Nitrilases are the enzymes widely expressed in prokaryotes and eukaryotes that hydrolyze non-peptide carbon-nitrogen bond (Pace and Brenner, 2001). These enzymes have become important tools in green chemistry to replace chemical hydrolysis, oxidation, reduction, etc. Nitrilases differ in substrate specifities and find applications in the transformation of a range of nitriles to acids (Banerjee et al, 2002). Initial investigations suggested that nitrilases were specific for aromatic nitriles while nitrile hydratases had affinity for aliphatic nitriles but this distinction has to be reconsidered in the light of rapidly growing information on nitrile degrading enzymes. How the amino acid sequence of nitrilase/s is related to specificity (aromaticity/aliphaticity) has not been much explored (Yeom et al, 2008)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
