A comparison of electrophoretic methods for isoenzyme characterization of trypanosomatids. I: Standard stocks of Trypanosoma cruzi zymodemes from northeast Brazil

Abstract An investigation of the relative merits of cellulose acetate electophoresis (CAE) and starch-gel electrophoresis (SGE) was made for 18 enzymes of T. cruzi using standard stocks of zymodemes Z1, Z2 and Z3. The 18 enzymes were those shown previously to be the most suited to routine screening of T. cruzi on starch-gel, namely, aspartate aminotransferase (E.C.2.6.1.1. ASAT); alanine aminotransferase (E.C.2.6.1.2. ALAT); phosphoglucomutase (E.C.-2.7.5.1. PGM); glucosephosphate isomerase (E.C.-5.3.1.9. GPI); malate dehydrogenase (oxaloacetate decarboxylating) (NADP + ) (E.C. 1.1.1.40. ME); glucose-6-phosphate dehydrogenase (E.C.1.1.1.49 G6PD); malate dehydrogenase (E.C. 1.1.1.37. MDH); aconitate hydratase (E.C.4.2.1.3. ACON); isocitrate dehydrogenase (NADP + ) (E.C.1.1.1.42. ICD); alcohol dehydrogenase (NADP + ) (E.C.-1.1.1.2. ADH); lactate dehydrogenase (E.C.1.1.1.27. LDH); aminopeptidase (cytosol) (E.G.3.4.11.1. PEP); pyruvate kinase (E.C.2.7.1.40. PK); phosphoglycerate kinase (E.C.2.7.2.3. PGK); enolase (E.C.4.2.1.11. ENO); hexokinase (E.C.2.7.1.1. HK); mannose phosphate isomerase (E.C.5.3.1.8. MPI); and glutamate dehydrogenase (E.C.1.4.1.2. GD). Of these MDH and PEP failed to give satisfactory patterns on CAE. The cellulose acetate zymograms of the other 16 enzymes were as good as, and in some cases better than, those of starch. Increased CAE resolution for ME and G6PD enabled all three zymodemes to be distinguished. Single CAE bands replaced double SGE bands in some cases, and vice versa, without affecting the zymodeme classification. It was concluded that CAE and SGE were both suitable for isoenzyme characterization and were complementary to each other. CAE characterization of T. cruzi was recommended for use in field work and simple laboratories because of its simplicity, transportability, low maintenance requirements and low capital expenditure. Isoelectric focusing (IEF) of ASAT, ALAT, GPI and PGM on Ampholine PAG plates gave poor results, in our hands, and was considered impracticable for routine characterization of T. cruzi .