Separation of carboxypeptidase A and B from longitudinal muscle layer of bovine small intestine: their properties regarding hydrolysis of enkephalins and enkephalin-analogs.

Carboxypeptidase A and B were partially purified from the soluble fraction of longitudinal muscle layer (myenteric plexus) of bovine small intestine. The obtained carboxypeptidase A hydrolyzed [Met]enkephalin-Arg6-Phe7 and [Leu]enkephalin, but [Met]enkephalin was not a suitable substrate for the enzyme. The Km value of carboxypeptidase A for [Met]enkephalin-Arg6-Phe7 was 0.74 mM and that for [Leu]enkephalin was 0.44 mM. Intestinal carboxypeptidase B hydrolyzed [Met]enkephalin-Arg6, liberating [Met]enkephalin, and the Km value of the enzyme for [Met]enkephalin-Arg6 was 0347 mM.