227] Histidine decarboxylase (mammalian)

Abstract

Publisher Summary This chapter discusses the methods of preparation of Histidine Decarboxylase (Mammalian). Two kinetically different histamine-forming enzymes or groups of enzymes have been demonstrated in mammalian tissues. One is possibly identical with the nonspecific aromatic L -amino acid decarboxylase also referred to as L -DOPA decarboxylase. Another appears to be specific and is probably of greater physiological significance as a catalyst of histamine formation. This enzyme is generally referred to as mammalian L -histidine decarboxylase or “specific” L -histidine decarboxylase. The “specific” histamine-forming enzyme has been found in a variety of tissues. Fetal rat tissues, hamster placenta, and murine mastocytoma are rich sources of this enzyme. Considerable activity has also been demonstrated in gastric mucosa, in red bone marrow, and in various transplantable tumors of the rat. In many tissues the enzyme activity is subject to considerable variation. The fact that tissues which are rich in “specific” histidine decarboxylase usually also contain the nonspecific enzyme presents another difficulty in investigations on the properties of histamine-forming enzymes.