Stimulation of mouse liver corticosteroid side chain isomerase by cobaltous and nickelous ions: Evidence for an endogenous inhibitor of isomerase activity

Iohan, F.; Monder, Carl

doi:10.1016/0003-9861(84)90424-7

Cited by 3 publications

(2 citation statements)

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“…Effects of Co2* and Ni2*. We have shown previously that cobaltous and nickelous ions stimulated isomerase activity of cytosol (Iohan & Monder, 1984;Purkaystha & Monder, 1981). In Figure 7, it is seen that these cations stimulated the purified enzyme, as well.…”

Section: Resultssupporting

confidence: 53%

“…Purification revealed other properties that were described by us in crude preparations, but that we could not be sure were intrinsic to the enzyme, and others that could be only studied adequately with the pure enzyme. For example, we concluded earlier that stimulation of isomerase by cobaltous ions was in part due to removal of an inhibitor from the incubation system (Iohan & Monder, 1984). That cobalt also stimulated the enzyme directly has now been shown with purified isomerase.…”

Section: Discussionmentioning

confidence: 74%

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Purification and characterization of corticosteroid side chain isomerase

Marandici

Monder²

1990

Biochemistry

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Corticosteroid side chain isomerase of rat liver catalyzes the interconversion of the ketol (20-oxo-21-ol) and aldol (20-hydroxy-21-al) forms of the corticosteroid side chain. The enzyme has now been purified to apparent homogeneity from rat liver cytosol by sequential chromatography on anionic, hydroxylapatite, and gel filtration columns. Ketol-aldol isomerization is followed by measuring the exchange of tritium from 21-tritiated steroids with water. The native enzyme is a dimer of MW 44,000. The isoelectric point is 4.8 +/- 0.1 pH units. The purified enzyme is stimulated by Co3+ or Ni2+. The enzyme utilizes 11-deoxycorticosterone, corticosterone, and 17-deoxycortisol as substrate but not cortisol, tetrahydrocortisol, and prednisolone. Tritium-water exchange of (21S)-[21-3H]DOC is a pseudo-first-order reaction; 21-3H exchange from the 21R isomer proceeds with first-order kinetics only after a lag associated with its epimerization to the 21S form.

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Section: Resultssupporting

confidence: 53%

Section: Discussionmentioning

confidence: 74%