|Reference : The Dmpa Aminopeptidase from Ochrobactrum Anthropi Lmg7991 Is the Prototype of a New Ter...|
|Scientific journals : Article|
|Life sciences : Biochemistry, biophysics & molecular biology|
|The Dmpa Aminopeptidase from Ochrobactrum Anthropi Lmg7991 Is the Prototype of a New Terminal Nucleophile Hydrolase Family|
|Fanuel, L. [> > > >]|
|Goffin, Colette [Université de Liège - ULg > > Centre d'ingénierie des protéines >]|
|Cheggour, A. [> > > >]|
|Devreese, B. [> > > >]|
|Van Driessche, G. [> > > >]|
|Joris, Bernard [Université de Liège - ULg > > Centre d'ingénierie des protéines >]|
|Van Beeumen, J. [> > > >]|
|Frère, Jean-Marie [Université de Liège - ULg > Département des sciences de la vie > Département des sciences de la vie >]|
|[en] The DmpA (d-aminopeptidase A) protein produced by Ochrobactrum anthropi hydrolyses p-nitroanilide derivatives of glycine and d-alanine more efficiently than that of l-alanine. When regular peptides are utilized as substrates, the enzyme behaves as an aminopeptidase with a preference for N-terminal residues in an l configuration, thus exemplifying an interesting case of stereospecificity reversal. The best-hydrolysed substrate is l-Ala-Gly-Gly, but tetra- and penta-peptides are also efficiently hydrolysed. The gene encodes a 375-residue precursor, but the active enzyme contains two polypeptides corresponding to residues 2-249 (alpha-subunit) and 250-375 (beta-subunit) of the precursor. Residues 249 and 250 are a Gly and a Ser respectively, and various substitutions performed by site-directed mutagenesis result in the production of an uncleaved and inactive protein. The N-terminal Ser residue of the beta-subunit is followed by a hydrophobic peptide, which is predicted to form a beta-strand structure. All these properties strongly suggest that DmpA is an N-terminal amidohydrolase. An exploration of the databases highlights the presence of a number of open reading frames encoding related proteins in various bacterial genomes. Thus DmpA is very probably the prototype of an original family of N-terminal hydrolases.|
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