Iron and aconitase activity

Abstract

Aconitase activated with Fe²⁺, cysteine and ascorbate incorporates 1 g-atom of Fe²⁺/mol. Loss of this Fe²⁺ by transfer to ferrozine, a Fe²⁺ chelator, results in loss of activity. Ascorbate increases the rate of transfer of the essential Fe²⁺ whereas citrate retards the rate of transfer. Transfer of Fe²⁺ from inactive aconitase, 2 g-atoms of Fe/mol, can be accomplished in the presence of urea and ascorbate. The correlation of activity with the presence of an added g-atom of Fe²⁺/mol leads to the conclusion that active aconitase has only one active site per mol.