δ‐Aminolevulinate Dehydratase from Rat Harderian Gland Purification and Properties

Abstract

δ‐Aminolevulinate dehydratase which catalyzes the second step in the biosynthesis of protoporphyrin has been purified from Harderian gland homogenates of normal rats. The enzyme preparation has a specific activity of 860 units per mg of protein at 37°, and about a 150‐fold purification from the crude extract has been achieved. The purified material appears to be homogeneous in starch gel and polyacrylamide gel disc electrophoretic studies. Partially purified enzyme preparations have an absolute requirement for cysteine or analogous thiol reagents. Effect of anions and cations is discussed.