title: A mechanism for the transfer of the carboxyl-group from 1'-N-carboxybiotin to acceptor substrates by biotin-containing enzymes.
abstract: Previous proposals for the mechanism by which biotin-dependent enzymes catalyse the transfer of the carboxyl group from 1'-N-carboxybiotin to acceptor molecules do not appear to be consistent with all of the experimental observations now available. We propose a multi-step mechanism in which (a) substrate and then carboxybiotin bind at the second partial reaction site, (b) a base positioned adjacent to the 3'-N of the carboxybiotin abstracts a proton from the 3'-N and (c) the resulting enolate ion and the acceptor substrate undergo a concerted reaction resulting in carboxyl-group transfer.
mesh_terms: D001665:Binding Sites; D001710:Biotin / Q000031:analogs & derivatives* / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000378:metabolism*; D007700:Kinetics; D008025:Ligases / Q000378:metabolism; D011485:Protein Binding; D011766:Pyruvate Carboxylase / Q000378:metabolism
chemical_list: C024582:N1'-carboxybiotin; D001710:Biotin; D002262:Carboxy-Lyases; D008025:Ligases; D011766:Pyruvate Carboxylase