Magnesium Dependent Phosphatase 1 (MDP1)

MDP-1, an enzyme of the haloacid dehalogenase family with a putative protein-tyrosine phosphatase function.Human recombinant MDP-1 acted on protein-bound fructosamine 6-phosphates with a catalytic efficiency >10-fold higher than those observed with its next best substrates (arabinose 5-phosphate and free fructoselysine 6-phosphate) and >100-fold higher than with protein-phosphotyrosine. It had no detectable activity on fructosamine 3-phosphates.

MDP-1 dephosphorylated up to ∼75% of the fructosamine 6-phosphates that are present on lysozyme after incubation of this protein with Glu-6-P. Furthermore, lysozyme glycated with Glu-6-P was converted by MDP-1 to a substrate for FN3K. MDP-1 may act physiologically in conjunction with FN3K to free proteins from the glycation products derived from Glu-6-P.