RESUMO
A series of substituted aryl malonamates have been prepared. These compounds are analogues of aryl phenaceturates where the amido side chain has been replaced by a retro-amide. Like the phenaceturates, these compounds are substrates of typical class A and class C beta-lactamases, particularly of the latter, and of soluble DD-peptidases. The effect of substituents alpha to the ester carbonyl group on turnover by these enzymes is similar to that in the phenaceturates. On the other hand, N-alkylation of the side chain amide of malonamates, but not of phenaceturates, retains the susceptibility of the compounds to hydrolysis by beta-lactamases. This reactivity is not enhanced, however, by bridging the amide nitrogen and Calpha atoms. A phosphonate analogue of the malonamates was found to be an irreversible inhibitor of the beta-lactamases. These results, therefore, provide further evidence for the covalent access of compounds bearing retro-amide side chains to the active sites of beta-lactam-recognizing enzymes.
Assuntos
Enterobacter/enzimologia , Malonatos/química , Malonatos/farmacologia , beta-Lactamases/metabolismo , Modelos Moleculares , Relação Estrutura-Atividade , Especificidade por Substrato , Inibidores de beta-Lactamases , beta-Lactamases/químicaRESUMO
The monobactam sodium 3-benzylcarbamoyl-2-oxo-1-azetidinesulfonate, bearing a retro (vs classical beta-lactam)-amide side chain, has been synthesized and the kinetics of its reaction with typical beta-lactamases studied. The new compound is generally a poorer substrate than the analogous compound with a normal side chain but its formation of a transiently stable complex with a class C beta-lactamase sustains the retro-amide side-chain concept.
Assuntos
Amidas/química , Monobactamas/química , Monobactamas/síntese química , beta-Lactamases/química , Catálise , Enterobacter cloacae/enzimologia , Hidrólise , Cinética , Conformação Molecular , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
3-(N-Benzylcarbamoyl)-7-carboxy-3, 4-dihydro-2H-1-benzo-pyran-2-one and its 8-carboxy analogue have been synthesized and evaluated as potential (inhibitory) substrates of beta-lactam-recognizing enzymes. These compounds are bicyclic delta-lactones with retro-amide (with respect to classical beta-lactams) side chains. They were found to be comparably effective as substrates of typical class A, C and D beta-lactamases as analogous benzopyranones bearing 'normal' amide side chains. The new 8-carboxy derivative, however, formed a much more (1000-fold) tightly-bound acyl-enzyme with a class C beta-lactamase than did its 'normal' analogue, and thus provides a structural lead to new inhibitors of this class of beta-lactamase.