Structure of an aliphatic amidase from Geobacillus pallidus RAPc8
| dc.contributor.author | Kimani, Serah W. | |
| dc.contributor.author | Agarkar, Vinod B. | |
| dc.contributor.author | Cowan, Donald A. | |
| dc.contributor.author | Sayed, Muhammed F. | |
| dc.contributor.author | Sewell, B. Trevor | |
| dc.date.accessioned | 2010-09-20T09:03:38Z | |
| dc.date.available | 2010-09-20T09:03:38Z | |
| dc.date.issued | 2007 | |
| dc.description.abstract | The amidase from Geobacillus pallidus RAPc8, a moderate thermophile, is a member of the nitrilase superfamily and catalyzes the conversion of amides to the corresponding carboxylic acids and ammonia. It shows both amide-hydrolysis and acyl-transfer activities and also exhibits stereoselectivity for some enantiomeric substrates, thus making it a potentially important industrial catalyst. The crystal structure of G. pallidus RAPc8 amidase at a resolution of 1.9 A ˚ was solved by molecular replacement from a crystal belonging to the primitive cubic space group P4232. G. pallidus RAPc8 amidase is homohexameric in solution and its monomers have the typical nitrilase-superfamily α-β-β-α fold. Association in the hexamer preserves the eight-layered α-β-β-α:α-β-β-α structure across an interface which is conserved in the known members of the superfamily. The extended carboxy-terminal tail contributes to this conserved interface by interlocking the monomers. Analysis of the small active site of the G. pallidus RAPc8 amidase suggests that access of a water molecule to the catalytic triad (Cys, Glu, Lys) side chains would be impeded by the formation of the acyl intermediate. It is proposed that another active-site residue, Glu142, the position of which is conserved in the homologues, acts as a general base to catalyse the hydrolysis of this intermediate. The small size of the substrate-binding pocket also explains the specificity of this enzyme for short aliphatic amides and its asymmetry explains its enantioselectivity. | en_US |
| dc.identifier.citation | Kimani, S.W., et al.(2007). The crystal structure of an aliphatic amidase from Geobacillus pallidus RAPc8: evidence for a fourth nitrilase catalytic residue. Acta Crystallographica. Section D: Biological Crystallography, 63:1048-1058. | |
| dc.identifier.uri | http://hdl.handle.net/10566/141 | |
| dc.language.iso | en | en_US |
| dc.privacy.showsubmitter | true | |
| dc.publisher | International Union of Crystallography | en_US |
| dc.rights | Copyright International Union of Crystallography. Publisher permits author to archive publisher pdf. | |
| dc.source.uri | http://dx.doi.org/10.1107/S090744490703836X | |
| dc.status.ispeerreviewed | true | |
| dc.subject | Geobacillus pallidus | en_US |
| dc.subject | Amidase | en_US |
| dc.subject | Industrial catalyst | en_US |
| dc.subject | Crystal structure | en_US |
| dc.subject | Hydrolase family | en_US |
| dc.title | Structure of an aliphatic amidase from Geobacillus pallidus RAPc8 | en_US |
| dc.type | Article | en_US |