Sub-banding and fine structure of serum lactate dehydrogenase isoenzymes induced by sulfur compounds

Human serum was incubated 1:1 by volume with solutions of several sulfur compounds of pH 7.2 for at least 24 hours and the total LDH-P determined and the distribution of LDH isoenzymes and fine structure examined by polyacrylamide disc electrophoresis. As with penicillamine, the disulfide but not N-acetyl-penicillamine, caused removal of LDH-5 without affecting the total unitage. The latter was depressed by thiophenoxyacetate (0.10-0.40 M), undiluted dimethyl sulfoxide and levamisole (0.025 M and higher) but not by the last agent at 0.0005-0.001 M which gave rise to fine structure in the gels. As screened in a number of sera of 160–2300 U/L in total LDH, phthalyltetrathioacetate (0.2-1.0 M) elicited 3 unique sub-bands as pre-LDH-2, pre-LDH-3 and pre-LDH-4 to the exclusion of any effect on the total LDH.