Lactate Dehydrogenase Isoenzymes in Chicken Tissues

Abstract

LACTATE dehydrogenase isoenzymes from a variety of animal sources have been reported to differ in a number of their properties, including substrate affinities^1,2, utilization of coenzyme analogues³, substrate specificity⁴, thermal stability⁵ and sensitivity to inhibitors^6,7. A regular gradation in these properties has been found which appears to correlate with the difference in electrophoretic mobility of each isoenzyme fraction. This difference is thought^8,9 to be determined by their A and B sub-unit composition. According to these workers,. LD₁ and LD₅ are “pure types” comprising four B and four A sub-units, respectively, and LD_2–4 are intermediate hybrid types. Cahn et al.⁹ report the presence of five lactate dehydrogenase isoenzymes in young chicken tissues, the heart muscle isoenzyme being a tetramer of four B sub-units and the breast muscle isoenzyme a tetramer of four A sub-units. We could not confirm the existence of five bands of activity in adult tissues, and this communication reports studies on isoenzymes derived from adult chicken tissues which showed different properties but similar electrophoretic mobility.