title: The 1.20 A resolution crystal structure of the aminopeptidase from Aeromonas proteolytica complexed with tris: a tale of buffer inhibition.
abstract: The aminopeptidase from Aeromonas proteolytica (AAP) is a bridged bimetallic enzyme that removes the N-terminal amino acid from a peptide chain. To fully understand the metal roles in the reaction pathway of AAP we have solved the 1.20 A resolution crystal structure of native AAP (PDB ID = 1LOK). The high-quality electron density maps showed a single Tris molecule chelated to the active site Zn(2+), alternate side chain conformations for some side chains, a sodium ion that mediates a crystal contact, a surface thiocyanate ion, and several potential hydrogen atoms. In addition, the high precision of the atomic positions has led to insight into the protonation states of some of the active site amino acid side chains.
authors.affiliation: Program in Biophysics and Structural Biology, Brandeis University, Waltham, Massachusetts 02454, USA.
authors.forename: William T
authors.initials: WT
authors.lastname: Desmarais
authors.forename: David L
authors.initials: DL
authors.lastname: Bienvenue
authors.forename: Krzysztof P
authors.initials: KP
authors.lastname: Bzymek
authors.forename: Richard C
authors.initials: RC
authors.lastname: Holz
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Petsko
authors.forename: Dagmar
authors.initials: D
authors.lastname: Ringe
mesh_terms: D000333:Aeromonas / Q000201:enzymology*; D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism; D000626:Aminopeptidases / Q000737:chemistry* / Q000378:metabolism; D001426:Bacterial Proteins; D001665:Binding Sites; D002614:Chelating Agents / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D015394:Molecular Structure; D011485:Protein Binding; D014325:Tromethamine / Q000737:chemistry* / Q000378:metabolism; D015032:Zinc / Q000378:metabolism
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D002614:Chelating Agents; D014325:Tromethamine; D000626:Aminopeptidases; C038222:bacterial leucyl aminopeptidase; D015032:Zinc