LACTATE-DEHYDROGENASE ISOENZYMES IN SERUM OF MAMMALIAN AND AVIAN ORIGIN

In the article we describe characteristics of lactate dehydrogenase (L D) (EC 1.1.1.27) isoenzymes of fowl origin. We compare them with chara cteristics of evolutionary different mammalian forms of the enzyme. Se parations of LD isoenzymes have been done using the most progressive e lectrophoretic techniques available at present. They included electrop horesis in homogeneous and gradient polyacrylamide gels (PAGE) as well as isoelectric focusing (IEF). A typical densitometric pattern of ser um LD isoenzymes obtained by gradient PAGE is illustrated in Fig. 1. I t is obvious that LD isoenzymes of all investigated animals have been well separated under applied experimental conditions, with an exceptio n of fowl serum. We succeeded in separating fowl LD isoenzymes using i soelectric focusing. It was possible to distinguish five fractions of lactate dehydrogenase (Fig. 2) by this technique.As shown in Fig. 2, m obility of avian isoenzymes in the gradient of pH differs from that of their mammalian analogues. Fowl LD isoenzymes were localized in catho dic part of IEF-gram. In the case of mammalian isoenzymes (cattle and rabbit), we found LD4 and LD5 forms of the enzyme in this part. The ma jor fractions, i. e. LD1 to LD3 were present in anodic part of IEF-gra m. We quantitatively expressed this different mobility of mammalian an d avian forms of LD using retention factors R(f) (Tab. III). A migrati on distance of cattle LD1 served as a reference point. It could be see n from a comparison of R(f) values that avian forms of LD (of galiform origin) differed from mammalian ones by an outstanding shift of their isoelectric points, especially that of LD1, toward basic values. The total LD activity (IU) and the relative distribution of the LD isoenzy me activities (%) in normal serum of various animals are listed in Tab s I and II. A comparison of these values showed that, in contrast to m ammalian serum (with the exception of the rat one), LDs was the predom inant fraction in fowl serum, followed by LD4. LD1 to LD3 occurred in low amounts with fairly similar proportions. On the other hand, most o f mammalian serum revealed a reverse pattern of LD isoenzymes, i. e. p redominant portion of serum activity had been concentrated in the firs t three anodic fractions and LD4 and LD5 had been found to be minor on es.