Stimulation of the hexose monophosphate pathway in the human erythrocyte by Mn2+: evidence for a Mn2+-dependent NADPH peroxidase activity.
In human RBC hemolysates, Mn2+ was found to stimulate the HMP as determined by the release of 14CO2 from [1-14C]glucose, providing activities of 125, 200, and 300% of basal at Mn2+ concentrations of 1, 10, and 100 mM, respectively. To explore the possibility that this stimulatory effect upon the HMP is a result of redox recycling of NADPH, RBC hemolysates were used to study NADPH oxidation. Mn2+, alone or in combination with a free radical-generating system, did not enhance the ability of hemolysates to oxidize NADPH. However, hemolysates + 10 mM H2O2 brought about a 10-fold increase in NADPH oxidation (0.51 +/- 0.05 nmole/min to 5.67 +/- 0.84 nmole/min) and the addition of 10 mM Mn2+ to this system increased the rate of oxidation to 34.10 +/- 2.97 nmole/min. Boiled hemolysates, either in the presence or absence of Mn2+, had some residual catalytic activity.
D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D008345:Manganese / Q000494:pharmacology*; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010427:Pentose Phosphate Pathway / Q000187:drug effects*; D010544:Peroxidases / Q000097:blood*; D013997:Time Factors
D008345:Manganese; D009249:NADP; D010544:Peroxidases; C045195:NADPH peroxidase