New Human Aldehyde Dehydrogenases

Abstract

Electrophoretic separation techniques of alcohol and aldehyde dehydrogenases have been generally employed for identification of the individual isozyme components. The electrophoretic patterns of alcohol dehydrogenase, a largely cathodal enzyme, are relatively easy to interpret because only a few other proteins migrate towards cathode and different isozymes have different isoelectric points. Aldehyde dehydrogenase, however, is largely an anodal enzyme, which migrates in the direction of the majority of other proteins, large numbers of which superimpose with aldehyde dehydrogenase. Some of these proteins produce gel bleaching during nitroblue tetrazolium / phenazine methosulfate color development and thereby mask some weaker aldehyde dehydrogenase bands. This is the reason why only the major bands of aldehyde dehydrogenase are usually visualized. In addition, there are several different aldehyde dehydrogenases that have the same pI as the major bands and therefore superimpose on isoelectric focusing gels. The superimposals that are now known to occur as a result of work of a large number of investigators (Greenfield and Pietruszko, 1977; Impraim et al., 1982; Jones and Teng, 1983; Palmer and Jenkins, 1985; Santisteban et al., 1985; Forte McRobbie and Pietruszko, 1986; Ryzlak and Pietruszko, 1988 a, b; Kurys et al., 1989; Wang et al., 1990) are shown in Table 1. The best known superimposals occur at pI 5.3 where the human E1 isozyme, human E3 isozyme and the Oriental E2 isozyme are found.