Reexamination of the interaction of cobaltous ions with the ketol side chain of corticosteroids

Purkaystha, Auditi; Monder, Carl

doi:10.1016/0022-4731(81)90355-1

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: 54%

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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: 54%

“…The possibility that the acceleration of C-21 tritium exchange with water is due to an interaction of cobaltous ions with the steroid side chain, leading to a stable enediol (Eger et al, 1972a,b), was excluded by us in earlier experiments (Purkaystha & Monder, 1981).…”

Section: Discussionmentioning

confidence: 95%