Interaction of N-succinyl-diaminopimelate desuccinylase with flavonoids.

DapE is an enzyme that belongs to the meso-diaminopimelate/Lysine pathway. It is recognized as an antimicrobial target, hence compounds that inhibit its catalytic activity are required. The principal features considered in the selection of potential inhibitors for this enzyme are compounds containing metal binding groups that could block access of the substrate to the Zinc metal centers and/or block the assembly of the oxyanion hole. We show the interaction of DapE from Enterococcus faecium, Staphylococcus aureus, Klebsiella aerogenes, Pseudomonas aeruginosa and Escherichia coli with flavonoids: quercetin, catechin, luteolin, rutin and hesperidin. Flavonoids contain several oxygen atoms distributed along their structure in a pattern that may be considered for the development of new antibiotics. Docking experiments suggest that these compounds containing metal binding groups that interact with metal centers of DapE and binding experiments indicate that glycoside flavonoids are preferred by DapE.

Inhibition of Urease by Disulfiram, an FDA-Approved Thiol Reagent Used in Humans.

Urease is a nickel-dependent amidohydrolase that catalyses the decomposition of urea into carbamate and ammonia, a reaction that constitutes an important source of nitrogen for bacteria, fungi and plants. It is recognized as a potential antimicrobial target with an impact on medicine, agriculture, and the environment. The list of possible urease inhibitors is continuously increasing, with a special interest in those that interact with and block the flexible active site flap. We show that disulfiram inhibits urease in Citrullus vulgaris (CVU), following a non-competitive mechanism, and may be one of this kind of inhibitors. Disulfiram is a well-known thiol reagent that has been approved by the FDA for treatment of chronic alcoholism. We also found that other thiol reactive compounds (l-captopril and Bithionol) and quercetin inhibits CVU. These inhibitors protect the enzyme against its full inactivation by the thiol-specific reagent Aldrithiol (2,2'-dipyridyl disulphide, DPS), suggesting that the three drugs bind to the same subsite. Enzyme kinetics, competing inhibition experiments, auto-fluorescence binding experiments, and docking suggest that the disulfiram reactive site is Cys592, which has been proposed as a "hinge" located in the flexible active site flap. This study presents the basis for the use of disulfiram as one potential inhibitor to control urease activity.