Uptake of protoporphyrin IX by isolated rat liver mitochondria

Uptake of protoporphyrin IX by isolated rat liver mitochondria.

Rat liver mitochondria accumulate protoporphyrin IX from the suspending medium into the inner membrane in parallel with the magnitude of the transmembrane K+ gradient (K+in/K+out). Only protoporphyrin IX taken up in parallel with the transmembrane K+ gradient is available for haem synthesis. Coproporphyrins (isomers I and III) are not taken up by the mitochondria. The results support the sugges...

The uptake of silicic acid by rat liver mitochondria.

1. To gain insight into a putative role for mitochondria in silicon metabolism, mitochondrial uptake (by which it is meant the removal from the medium) of silicic acid [Si(OH)4] was studied under conditions minimizing SI(OH)4 polymerization. 2. Measurements of mitochondrial respiration and swelling indicated indirectly a significant uptake of Si(OH)4 as a weak acid, but this was not confirmed w...

The uptake of thyroxine and triiodothyronine by rat-liver mitochondria.

The initial velocities of calcium uptake by rat liver mitochondria.

Initial velocities of energy-dependent Ca++ uptake were measured in rat liver mitochondria by stopped flow techniques and dual wave length spectroscopy in the presence of the Ca++ indicator murexide. The initial rate of energy-dependent Ca++ uptake by mitochondria was 0.1 to 0.3 nmole per s per mg of protein at 5 to 15 pM Ca++, and increased to 8.2 nmoles of Ca++ per s per mg at 200 PM Ca++. Wh...

Biosynthesis of cytochrome c oxidase by isolated rat liver mitochondria.

When isolated mitochondria which have been labeled with [3H]leucine are solubilized and treated with anti-serum specific for cytochrome c oxidase, labeled polypeptides which correspond to the three largest polypeptides of this enzyme are immunoprecipitated. This indicates that the three largest polypeptides of cytochrome c oxidase which have Mr of 66,000, 39,000, and 23,000 are synthesized by i...