Aconitase Activity, Citrate Oxidation, and Zinc Inhibition in Rat Ventral Prostate

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Abstract
Aconitase activity and citrate oxidation were determined in mitochondrial preparations from rat ventral prostate. Aconitase activity in prostate mitochondria was .apprx. 10% of the activity observed in kidney preparations. The prostate aconitase activity was completely inhibited by the addition of 1.0 mmol/l Zn and kidney aconitase was inhibited by .apprx. 50%. The presence of 1.0 mmol/l Zn also markedly inhibited the formation of isocitrate from cis-aconitate. The reduction of NADP by citrate was markedly inhibited (.apprx. 95%) by 1.0 mmol/l Zn as compared with a 70 and 40% inhibition of aconitate- and isocitrate- stimulated reduction, respectively. Zn might be a strong inhibitor of aconitase activity with an inhibitory effect on isocitrate dehydrogenase also. The effect of 1.0 mmol/l Zn on citrate oxidation was studied by determining 14CO2 production from 6-14C-citrate. 14CO2 was significantly inhibited by Zn. Citrate accumulation in prostate might be the result of limited citrate oxidation which results from a combination of low aconitase activity and possibly Zn inhibition.