Kinetic and theoretical study of the chalcones as inhibitors of beta-lactamase enzyme.
Staphyloccoccus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii, Enterobacter cloacae and more bacteria have shown resistance to antibiotics in Colombia, therefore, resistance to antibiotics is a problem that is on increase in Colombia. The resistance mechanism to penicillin antibiotics in these bacteria is the expression of beta-Lactamase enzyme. In order to use the penicillin antibiotics which are still effective against them, we had evaluated 10 chalcones as inhibitors of this enzyme. The most active chalcone showed K(m') = 406.7 microM higher than clavulanic acid that showed K(m') = 211.9 microM at 37 degrees C during 10 h, and using amoxycillin as substrate. The chalcones were better competitive inhibitors because of they allowed the hydrolysis of smaller quantity of amoxycillin than the clavulanic acid, the most active chalcone showed K(cat)/K(M) = 1.398 (minM)(-1) and the clavulanic acid showed K(cat)/K(M) = 2.674 (minM)(-1). The molecular modelling of the Enzyme-chalcones complexes showed that the chalcones with electron-donating groups on ortho, meta position of A ring favour the interaction with the residues Threonine-319, Lysine-67, Serine-64 and Tyrosine-150 of the active site of the enzyme, because of the number and strong of Hydrogen bonds of the chalcones in the active site of the enzyme increase, and therefore the affinity of the chalcones increases too. The electron-donating groups in the chalcones contribute to their inductive effect improving the interaction with the active site of the enzyme because of rising of electrostatic attraction between them.
Laboratorio de Sustancias Bioactivas, Sede de Investigación Universitaria, Universidad de Antioquia. Carr. 53 61-30. Medellín, Colombia. consuelo.jaramillo@gmail.com
M Consuelo
MC
Jaramillo
Cristina
C
Mora
Luís E
LE
Vélez
Jairo
J
Quijano
D047188:Chalcones / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D004583:Electrons; D016972:Enterobacter cloacae / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000737:chemistry / Q000378:metabolism*
D047188:Chalcones; D004791:Enzyme Inhibitors; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases