Question

Phosphonatase uses Mg2+ cofactor. Describe how it assists in the catalysis. Describe how phosphonatase uses the active site Histidine 56 to avoid the formation of high energy transition states along the chemical pathway defined by the K53 and Asp12 catalytic groups.(what is His56 doing in each of the transition states)

Answer 1

.Phosphonatase catalyzes the hydrolysis of phosphonoacetaldehyde to acetaldehyde and inorganic phosphate by cleavage of P-C bond. The mechanism involves Schiff-base (imine) formation also called Schiff-base mechanism.. According to this mechanism, the reaction starts by a nucleophilic attack of a neutral amine (Lys 53 residue) on the carbon atom in the carbonyl group of the substrate. Simultaneously a proton is transferred to the oxygen atom of the carbonyl group. After elimination of a hydroxide, the Schiff-base is formed and finally the phosphoryl group is transferred to Asp12.