Iron dependence and zinc inhibition of duodenal cytosolic aconitase of rat.
The response of duodenal cytosolic aconitase (c-aconitase) to oral repletion of graded doses of iron (Fe) during Fe-deficiency was studied in rats (WNIN strain). In addition, in vitro effect of zinc (Zn) on the enzyme activity was studied using duodenal cytosol. Iron-depleted male rats were orally repleted with either 100 or 190 or 370 microg of Fe/day (n=6, each) for 2 weeks. Fe repletion was found to increase linearly the activity of duodenal c-aconitase along with the indicators of iron status. The correlation coefficient (r) between c-aconitase and haemoglobin and mucosal ferritin was 0.6453 and 0.8441, respectively. The effects of zinc (0-40 microM) in vitro on the kinetics of c-aconitase from iron-replete stock diet fed rats (n=4) showed that Zn competitively inhibited the enzyme with a Ki (app.) of 28 microM. These observations suggest that c-aconitase is a critical target involved in the assimilation of Fe and excess dietary Zn can result in negative interactions.
Biophysics Division, National Institute of Nutrition, Hyderabad 500007, India.
Bodiga
B
Sreedhar
K Madhavan
KM
Nair
D000154:Aconitate Hydratase / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D000818:Animals; D027682:Cation Transport Proteins / Q000378:metabolism; D003593:Cytoplasm; D003600:Cytosol / Q000201:enzymology* / Q000378:metabolism; D004386:Duodenum / Q000201:enzymology; D004847:Epithelial Cells / Q000201:enzymology; D007413:Intestinal Mucosa / Q000378:metabolism; D007501:Iron / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D051381:Rats; D015032:Zinc / Q000737:chemistry / Q000494:pharmacology*; D000099236:Solute Carrier Family 11, Member 2
D000154:Aconitate Hydratase; D027682:Cation Transport Proteins; D007501:Iron; D015032:Zinc; D000099236:Solute Carrier Family 11, Member 2