Immunochemical studies with citrate-condensing enzyme

Abstract

Anti-enzyme to citrate-condensing enzyme from pig heart was prepared in rabbits. The interaction of the enzyme and anti-enzyme was not dependent on pH between 6.3 and 8.9 nor was it dependent on temperature at 0[deg] or 37[deg]. The reaction was complete within 10 min of mixing the enzyme and its anti-enzyme. The presence of heat-inactivated enzyme, acetyl-CoA, CoA or citrate did not affect the interaction of active enzyme and anti-enzyme; enzyme inactivated by acetylation retained some reactivity for anti-enzyme. p-Mercuribenzoate-treated enzyme interacted with the anti-enzyme in a manner indistinguishable from untreated enzyme. The enzymes from pig liver and kidney and pigeon heart and breast muscle could not be distinguished from pig-heart enzyme on the basis of their reactivity with the pig-heart anti-enzyme; enzyme from pigeon liver and dog heart, liver and kidney reacted partially whereas that from moth flight muscle and rabbit heart remained completely uninhibited in the presence of pig-heart anti-enzyme. The suggestion is made that the catalytic center and the antigenic determinant may occupy neighboring areas.