Diiodothyronines (3,3′-T2 and 3,5-T2) stimulate the activity of isolated cytochrome c oxidase (COX) from bovine heart mitochondria. Maximal stimulation of activity (about 50%) is obtained with 3,3′-T2 at pH 6.4 and with 3,5-T2 at pH 7.4. In contrast, 3,5,3′-triiodothyronine (T3) exhibited no or little stimulation of COX activity. Binding of the hormones to COX leads to conformational changes as shown by modified visible spectra of the oxidized enzyme. It is suggested that 'short-term' effects of thyroid hormones on mitochondrial respiration are at least partly due to the allosteric interaction of diiodothyronines with the COX complex. © 1994.
INTERACTION OF DIIODOTHYRONINES WITH ISOLATED CYTOCHROME-C-OXIDASE
LANNI, Antonia;
1994
Abstract
Diiodothyronines (3,3′-T2 and 3,5-T2) stimulate the activity of isolated cytochrome c oxidase (COX) from bovine heart mitochondria. Maximal stimulation of activity (about 50%) is obtained with 3,3′-T2 at pH 6.4 and with 3,5-T2 at pH 7.4. In contrast, 3,5,3′-triiodothyronine (T3) exhibited no or little stimulation of COX activity. Binding of the hormones to COX leads to conformational changes as shown by modified visible spectra of the oxidized enzyme. It is suggested that 'short-term' effects of thyroid hormones on mitochondrial respiration are at least partly due to the allosteric interaction of diiodothyronines with the COX complex. © 1994.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
