METHODS FOR THE SEPARATION OF LACTATE-DEHYDROGENASES AND CLINICAL-SIGNIFICANCE OF THE ENZYME

Lactate dehydrogenase (LDH), an ubiquitous enzyme among vertebrates, i nvertebrates, plants and microbes was discovered in the early period o f enzymology. The enzyme has been dissolved in several distinguishable molecular forms. In mammals, three types of subunits encoded by the g enes Ldh-A, Ldh-B and Ldh-C give rise to a selected number of tetramer ic isoenzymes. LDH-A(4), LDH-B-4 and the mixed hybrid forms of the A- and B-subunits are present in many tissues but with certain distributi on patterns. LDH-C-4 is confined in mammals to testes and sperm. Numer ous techniques have been employed to purify, characterize and separate the different forms of the enzyme. This report deals with the main pr otocols and procedures of purification of LDH and its isoenzymes inclu ding chromatographic and electrophoretic methods, partitioning in aque ous two-phase systems and precipitation approaches. In particular, aff inity separation techniques based on natural and pseudo-biospecific li gands are described in detail. In addition, basic physico-chemical and kinetic properties of the enzyme from different sources are summarize d. In a second part, the clinical significance of the determination of LDH in diverse body fluids in respect to the total activity and the i soenzyme distribution in different organs is discussed.