Inhibition and activation of human lactate dehydrogenase by urea

Abstract

The degree of inhibition or activation at 37°C by urea of human lactate dehydrogenase (LDH) isoenzymes was established with pyruvate, 2 oxobutyrate, and hydroxypyruvate as substrates. Lactate dehydrogenase activation was demonstrated in the presence of low concentrations of urea. The protective effect of urea against enzyme inhibition by increased substrate concentrations was also confirmed. Clinical studies indicate that urea inhibition is a practical and potentially valuable tool in the assessment of LDH isoenzyme patterns at 37°C.