3o4j

Structure and Catalysis of Acylaminoacyl Peptidase

spinqualitylabelsall models 3o4j, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3o4j is a 4 chain structure with sequence from Aerpx. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CL, GOL, NA Related: 3o4g, 3o4h, 3o4i Gene: APE_1547.1 (AERPX) Activity: Acylaminoacyl-peptidase, with EC number 3.4.19.1 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [APEH_AERPE] This enzyme catalyzes the hydrolysis of the N-terminal peptide bond of an N-acetylated peptide to generate an N-acetylated amino acid and a peptide with a free N-terminus. Publication Abstract from PubMed Acylaminoacyl peptidase from Aeropyrum pernix is a homodimer that belongs to the prolyl oligopeptidase family. The monomer subunit is composed of one hydrolase and one propeller domain. Previous crystal structure determinations revealed that the propeller domain obstructed the access of substrate to the active site of both subunits. Here we investigated the structure and the kinetics of two mutant enzymes in which the aspartic acid of the catalytic triad was changed to alanine or asparagine. Using different substrates, we have determined the pH dependence of specificity rate constants, the rate-limiting step of catalysis, the binding of substrates and inhibitors. The catalysis considerably depended both on the kind of mutation and on the nature of the substrate. The results were interpreted in terms of alterations in the position of the catalytic histidine side chain as demonstrated with crystal structure determination of the native and the two mutant structures (D524N, D524A). Unexpectedly, in the homodimeric structures, only one subunit displayed the closed form of the enzyme. The other subunit exhibited an open gate to the catalytic site, thus revealing the structural basis that controls the oligopeptidase activity. The open form of the native enzyme displayed the catalytic triad in distorted, inactive state. The mutations affected the closed, active form of the enzyme, disrupting its catalytic triad. It is concluded that the two forms are at equilibrium, and the substrates bind by the conformational selection mechanism. Structure and catalysis of acylaminoacyl peptidase: closed and open subunits of a dimer oligopeptidase.,Harmat V, Domokos K, Menyhard DK, Pallo A, Szeltner Z, Szamosi I, Beke-Somfai T, Naray-Szabo G, Polgar L J Biol Chem. 2010 Nov 16. PMID:21084296 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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