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Zinc causes a shift toward citrate at equilibrium of the m-aconitase reaction of prostate mitochondria.
J Inorg Biochem. 2000 Jan 30; 78(2):161-5.JI

Abstract

Prostate secretory epithelial cells have the unique function and capability of accumulating and secreting extraordinarily high levels of citrate. To achieve this, these cells possess a uniquely limiting mitochondrial (m)-aconitase activity that minimizes the oxidation of citrate via the Krebs cycle. The steady-state citrate/isocitrate ratio of mammalian tissues is generally maintained at about 10-11/l, independent of the concentration of citrate, which is the result of the chemical equilibrium reached in the presence of m-aconitase. In contrast, the citrate/isocitrate ratio of prostate tissue is about 30-40/l. Zinc, which is also accumulated in prostate cells at much higher levels than in other cells, inhibits m-aconitase activity thereby minimizing citrate oxidation. This current report is concerned with an effect of zinc on the equilibrium of the reaction catalyzed by m-aconitase. Studies were conducted with mitochondrial extract preparations from rat ventral prostate epithelial cells. With citrate as the initial substrate, the addition of zinc (7-10 microM) to the prostate mitochondrial preparation resulted in a change in the citrate/isocitrate ratio at equilibrium from an average of 10.5/l to 13.5/l. In contrast, the identical treatment of kidney mitochondrial preparations resulted in no zinc-induced change in the citrate/isocitrate ratio. When either cis-aconitate or isocitrate was employed as the initial substrate, the addition of zinc did not alter the citrate/isocitrate ratio of prostate or kidney preparations. Partial purification of the prostate preparation revealed that the prostate mitochondrial extract contained a putative protein (which we have designated as 'citrate factor protein') that is required for the zinc-induced increase in the citrate/isocitrate ratio. This novel effect of zinc provides another mechanism by which it is assured that the accumulation of citrate is maximized in citrate-producing prostate epithelial cells.

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Authors+Show Affiliations

Costello LC
Cellular and Molecular Biology Section, OCBS/Dental School, University of Maryland, Baltimore 21201, USA. lcc001@dental.umaryland.edu
Franklin RB
No affiliation info available
Liu Y
No affiliation info available
Kennedy MC
No affiliation info available

MeSH

Aconitate HydrataseAnimalsMaleMitochondriaProstateRatsRats, WistarZinc

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

10766339

Citation

Costello, L C., et al. "Zinc Causes a Shift Toward Citrate at Equilibrium of the M-aconitase Reaction of Prostate Mitochondria." Journal of Inorganic Biochemistry, vol. 78, no. 2, 2000, pp. 161-5.
Costello LC, Franklin RB, Liu Y, et al. Zinc causes a shift toward citrate at equilibrium of the m-aconitase reaction of prostate mitochondria. J Inorg Biochem. 2000;78(2):161-5.
Costello, L. C., Franklin, R. B., Liu, Y., & Kennedy, M. C. (2000). Zinc causes a shift toward citrate at equilibrium of the m-aconitase reaction of prostate mitochondria. Journal of Inorganic Biochemistry, 78(2), 161-5.
Costello LC, et al. Zinc Causes a Shift Toward Citrate at Equilibrium of the M-aconitase Reaction of Prostate Mitochondria. J Inorg Biochem. 2000 Jan 30;78(2):161-5. PubMed PMID: 10766339.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Zinc causes a shift toward citrate at equilibrium of the m-aconitase reaction of prostate mitochondria. AU - Costello,L C, AU - Franklin,R B, AU - Liu,Y, AU - Kennedy,M C, PY - 2000/4/15/pubmed PY - 2000/4/29/medline PY - 2000/4/15/entrez SP - 161 EP - 5 JF - Journal of inorganic biochemistry JO - J Inorg Biochem VL - 78 IS - 2 N2 - Prostate secretory epithelial cells have the unique function and capability of accumulating and secreting extraordinarily high levels of citrate. To achieve this, these cells possess a uniquely limiting mitochondrial (m)-aconitase activity that minimizes the oxidation of citrate via the Krebs cycle. The steady-state citrate/isocitrate ratio of mammalian tissues is generally maintained at about 10-11/l, independent of the concentration of citrate, which is the result of the chemical equilibrium reached in the presence of m-aconitase. In contrast, the citrate/isocitrate ratio of prostate tissue is about 30-40/l. Zinc, which is also accumulated in prostate cells at much higher levels than in other cells, inhibits m-aconitase activity thereby minimizing citrate oxidation. This current report is concerned with an effect of zinc on the equilibrium of the reaction catalyzed by m-aconitase. Studies were conducted with mitochondrial extract preparations from rat ventral prostate epithelial cells. With citrate as the initial substrate, the addition of zinc (7-10 microM) to the prostate mitochondrial preparation resulted in a change in the citrate/isocitrate ratio at equilibrium from an average of 10.5/l to 13.5/l. In contrast, the identical treatment of kidney mitochondrial preparations resulted in no zinc-induced change in the citrate/isocitrate ratio. When either cis-aconitate or isocitrate was employed as the initial substrate, the addition of zinc did not alter the citrate/isocitrate ratio of prostate or kidney preparations. Partial purification of the prostate preparation revealed that the prostate mitochondrial extract contained a putative protein (which we have designated as 'citrate factor protein') that is required for the zinc-induced increase in the citrate/isocitrate ratio. This novel effect of zinc provides another mechanism by which it is assured that the accumulation of citrate is maximized in citrate-producing prostate epithelial cells. SN - 0162-0134 UR - https://www.unboundmedicine.com/medline/citation/10766339/Zinc_causes_a_shift_toward_citrate_at_equilibrium_of_the_m_aconitase_reaction_of_prostate_mitochondria_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0162-0134(99)00225-1 DB - PRIME DP - Unbound Medicine ER -