RESUMO
The inhibition of alkaline phosphatases by calix[4]arenes functionalysed at the macrocyclic upper rim by one or two methylenebisphosphonic acid fragments has been investigated. It is established, that calix[4]arene bismethylenebisphosphonic acid displayed stronger inhibition of alkaline phosphatase from bovine intestine mucosa than calix[4]arene methylenebisphosphonic acid. At the same time, the both inhibitors showed almost similar levels of inhibitory activities in respect of bovine kidney alkaline phosphatase or E. coli alkaline phosphatase. The tested compounds were docked computationally to the active site of the E. coli alkaline phosphatase. On the basis of results obtained the possible binding modes of inhibitors were analysed.
Assuntos
Fosfatase Alcalina/antagonistas & inibidores , Calixarenos/farmacologia , Inibidores Enzimáticos/farmacologia , Compostos Organofosforados/farmacologia , Fenóis/farmacologia , Animais , Sítios de Ligação , Calixarenos/química , Bovinos , Inibidores Enzimáticos/química , Escherichia coli/enzimologia , Mucosa Intestinal/enzimologia , Intestino Delgado/enzimologia , Rim/enzimologia , Modelos Moleculares , Estrutura Molecular , Fenóis/químicaRESUMO
The effect of L-cysteine on activity of hydrophobic forms of calf intestine alkaline phosphatase was investigated. Apparent inhibition constants for mixed type inhibition have been determined. The kinetic results allow supposing that the mechanism of equilibrium establishment between the inhibitor and enzyme involves the initial rapid formation of intermediate complex and a subsequent slower step leading to its stabilization in the substrate binding site. The microscopic rate constants for slow step of interaction of L-cysteine with alkaline phosphatase have been calculated. Effect of pH on apparent inhibition constants and kinetic parameters for enzymatic reaction in the presence of L-cysteine was analysed.