title: Mechanistic similarity and diversity among the guanidine-modifying members of the pentein superfamily.
abstract: The pentein superfamily is a mechanistically diverse superfamily encompassing both noncatalytic proteins and enzymes that catalyze hydrolase, dihydrolase and amidinotransfer reactions on guanidine substrates. Despite generally low sequence identity, they possess a conserved structural fold and display common mechanistic themes in catalysis. The structurally characterized catalytic penteins possess a conserved core of residues that include a Cys, His and two polar, guanidine-binding residues. All known catalytic penteins use the core Cys to attack the substrate's guanidine moiety to form a covalent thiouronium adduct and all cleave one or more of the guanidine C--N bonds. The mechanistic information compiled to date supports the hypothesis that this superfamily may have evolved divergently from a catalytically promiscuous ancestor.
authors.affiliation: Graduate Program in Biochemistry, The University of Texas at Austin, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Linsky
authors.forename: Walter
authors.initials: W
authors.lastname: Fast
mesh_terms: D000818:Animals; D002384:Catalysis; D004798:Enzymes / Q000737:chemistry* / Q000378:metabolism*; D019791:Guanidine / Q000737:chemistry*; D006801:Humans; D008958:Models, Molecular; D005810:Multigene Family
chemical_list: D004798:Enzymes; D019791:Guanidine