L(+)‐lactate Dehydrogenase in the Human Oral Cavity

Extracellular Administration of Lactate Dehydrogenase and Its Effects on Human Plaque pH and Acid Anion Concentrations

“…Significantly lower concen trations of lactate in plaque fluid were observed fol lowing rinsing with sucrose containing 2 U/ml LDH than with the lower concentration of the enzyme. LDH is the terminal enzyme of the Embden-Meyerhof pathway and intracellularly catalyses the conver sion of pyruvate to lactate [Eichel et al, 1965], Extracellularly, LDH is capable, under appropriate condi tions, of catalysing the oxidation of lactate to pyru vate [Calandra and Adams, 1951], It is this reaction that is thought to be responsible for the reduction in the accumulation of lactate in human dental plaque following rinsing with solutions containing LDH. Hydrogen acceptors are thought to be present extracellularly, possibly from cell death and lysis and from pyruvate catalysis of the oxidation of NADH during the biosynthesis of amino-acids [Somerville, 1968], in concentrations which permit the oxidation of lactate to proceed despite the equilibrium of the reaction which is in favour of lactate synthesis.…”

Effects of Lactate Dehydrogenase on Fissure Caries in Rats

“…Lactate dehydrogenase is the terminal enzyme of the Embden-Meyerhof pathway and is a widely distri buted intracellular enzyme which catalyses the con version of pyruvate to lactate [Eichel et al, 1965]. LDH mutants of streptococci have decreased cario genic potential and this has been shown to be directly related to a decrease in acid production [Johnson et al, 1980], Similarly, studies in rats have shown that LDH mutants of Streptococcus mutans are less cario genic than the wild types due to the production of eth anol, acetic acid and acetone, rather than lactate from glucose [Fitzgerald et al, 1988].…”