title: Insights into acylphosphatase structure and catalytic mechanism.
abstract: Acylphosphatase is one of the smallest enzymes known (about 98 amino acid residues). It is present in organs and tissues of vertebrate species as two isoenzymes sharing over 55% of sequence homology; these appear highly conserved in differing species. The two isoenzymes can be involved in a number of physiological processes, though their effective biological function is not still certain. The solution and crystal structures of different isoenzymes are known, revealing a close packed protein with a fold similar to that shown by other phosphate-binding proteins. The structural data, together with an extended site-directed mutagenesis investigation, led to the identification of the residues involved in enzyme catalysis. However, it appears unlikely that these residues are able to perform the full catalytic cycle: a substrate-assisted catalytic mechanism has therefore been proposed, in which the phosphate moiety of the substrate could act as a nucleophile activating the catalytic water molecule.
authors.affiliation: Department of Biochemical Sciences, University of Florence, Italy. stefani@cesit1.unifi.it
authors.forename: M
authors.initials: M
authors.lastname: Stefani
authors.forename: N
authors.initials: N
authors.lastname: Taddei
authors.forename: G
authors.initials: G
authors.lastname: Ramponi
mesh_terms: D017766:Acid Anhydride Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002384:Catalysis; D004795:Enzyme Stability; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011487:Protein Conformation; D000097024:Acylphosphatase
chemical_list: D017766:Acid Anhydride Hydrolases; D007527:Isoenzymes; D000097024:Acylphosphatase