THE NADP-LINKED ALDEHYDE REDUCTASE OF LEISHMANIA-DONOVANI

An enzyme that oxidizes ethanol to acetaldehyde in the presence of NAD P (but not NAD) and reduces acetaldehyde to ethanol in the presence of NADPH (but not NADH) is present in Leishmania donovani promastigotes. The activity is present only in the supernatant fraction obtained fro m sonication of the cells and high speed centrifugation. The Km and Vm values were evaluated for propanol and propionaldehyde as well as for ethanol and acetaldehyde in cells obtained from late log and 3-day st ationary phase cultures. There was no significant change in Km or Vm v alues for any of these four substrates with culture age. Since the Km values for ethanol and propanol are much higher than for the correspon ding aldehydes and higher than any physiological range of alcohol conc entration likely to be encountered, this enzyme is considered to funct ion as an aldehyde reductase.