Structure of an aliphatic amidase from Geobacillus pallidus RAPc8

dc.contributor.authorKimani, Serah W.
dc.contributor.authorAgarkar, Vinod B.
dc.contributor.authorCowan, Donald A.
dc.contributor.authorSayed, Muhammed F.
dc.contributor.authorSewell, B. Trevor
dc.date.accessioned2010-09-20T09:03:38Z
dc.date.available2010-09-20T09:03:38Z
dc.date.issued2007
dc.description.abstractThe 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.citationKimani, 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.urihttp://hdl.handle.net/10566/141
dc.language.isoenen_US
dc.privacy.showsubmittertrue
dc.publisherInternational Union of Crystallographyen_US
dc.rightsCopyright International Union of Crystallography. Publisher permits author to archive publisher pdf.
dc.source.urihttp://dx.doi.org/10.1107/S090744490703836X
dc.status.ispeerreviewedtrue
dc.subjectGeobacillus pallidusen_US
dc.subjectAmidaseen_US
dc.subjectIndustrial catalysten_US
dc.subjectCrystal structureen_US
dc.subjectHydrolase familyen_US
dc.titleStructure of an aliphatic amidase from Geobacillus pallidus RAPc8en_US
dc.typeArticleen_US

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