Enzymes of heme metabolism is the kidney. Regulation by trace metals which do not form heme complexes

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Abstract
The in vivo regulation by metal ions of the enzymes of heme metabolism in kidney-particularly of ALAS, the rate-limiting enzyme in heine formation- was investigated. Ni(2+) and Pt(4+), metals which do not enzymatically form metalloporphyrins, were found to regulate ALAS in kidney as they do in liver. The pattern of this regulation was generally similar to that observed with heme and metal ions in liver, i.e., a late increase in enzyme activity after an early period in which ALAS activity was unaltered or inhibited. The metals did not interact with the enzyme in vitro to alter its activity. In this study no direct reciprocal relationship between ALAS activity and total cellular heine content was demonstrated. The metal ions, particularly Pt(4+), also altered the activity of other enzymes of heme biosynthesis in kidney. Pt(4+) severely inhibited the activity of ALAD and UROS. Ni(2+) and Pt(4+) were potent inducers of heme oxygenase, the initial and rate-limiting enzyme in heine degradation.

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