Purification and Characterization of 3,4‐Dihydroxyphenylalanine Decarboxylase from Pig Kidney

Abstract

A procedure for 3,4-dihydroxyphenylalanine decarboxylase from pig kidney purification is described in detail. The preparation has no detectable impurity on elecrophoresis and on ultracentrifugation and has a coenzyme content and a specific activity comparable with the same enzyme purified by other authors. However two significant differences are observed: a different stimulation of activity by added pyridoxal 5′-phosphate and a nearly complete decarboxylation of L-3,4-dihydroxyphenylalanine in absence of added coenzyme. Absorption, fluorescence and circular dichroism properties of the coenzyme-apoenzyme interaction are also described. The results are consistent with the existence of at least four coenzyme-apoenzyme complexes, three of them active.