RESUMO
Pantothenate synthetase catalyses the ATP-dependent condensation of D-pantoate and beta-alanine to form pantothenate. Ten analogues of the reaction intermediate pantoyl adenylate, in which the phosphodiester is replaced by either an ester or sulfamoyl group, were designed as potential inhibitors of the enzyme. The esters were all modest competitive inhibitors, the sulfamoyls were more potent, consistent with their closer structural similarity to the pantoyl adenylate intermediate.
Assuntos
Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacologia , Escherichia coli/enzimologia , Peptídeo Sintases/antagonistas & inibidores , Trifosfato de Adenosina/farmacologia , Inibidores Enzimáticos/química , Escherichia coli/efeitos dos fármacos , Ésteres/química , Cinética , Modelos Moleculares , Peptídeo Sintases/química , Estrutura Secundária de Proteína , Sulfonamidas/química , TemperaturaRESUMO
We report the crystal structure of E. coli ketopantoate hydroxymethyltransferase (KPHMT) at 1.9 A resolution, in complex with its product, ketopantoate. KPHMT catalyzes the first step in the biosynthesis of pantothenate (vitamin B(5)), the precursor of coenzyme A and the acyl carrier protein cofactor. The structure of the decameric enzyme was solved by multiwavelength anomalous dispersion to locate 160 selenomethionine sites and phase 560 kDa of protein, making it the largest structure solved by this approach. KPHMT adopts the (betaalpha)(8) barrel fold and is a member of the phosphoenolpyruvate/pyruvate superfamily. The active site contains a ketopantoate bidentately coordinated to Mg(2+). Similar binding is likely for the substrate, alpha-ketoisovalerate, orienting the C3 for deprotonation.
