Fe (II)/Cu (I)-dependent P-type ATPase activity in the liver of long-evans cinnamon rats

K Takeda, H Eguchi, S Soeda, A Shirahata… - Life sciences, 2005 - Elsevier
K Takeda, H Eguchi, S Soeda, A Shirahata, M Kawamura
Life sciences, 2005Elsevier
This study examined Fe (II)-dependent ATPase activity in OTG (octylthioglucoside)-treated
microsomes isolated from Wistar and LEC rats. The ATPase activity of the liver OTG-
microsomes from Wistar rats increased sharply in the 5–150 μM range of Fe (II) with a K0. 5
value of 23.9±3.6 μM, while the activity of LEC rat liver microsomes increased with
increasing Fe (II) up to 500 μM with a K0. 5 value of 64.4±8.1 μM. The K0. 5 values for Fe (II)-
dependent ATPase activity of spleen OTG-microsomes were nearly identical at 59.3 μM in …
This study examined Fe(II)-dependent ATPase activity in OTG (octylthioglucoside) -treated microsomes isolated from Wistar and LEC rats. The ATPase activity of the liver OTG-microsomes from Wistar rats increased sharply in the 5 – 150 μM range of Fe(II) with a K0.5 value of 23.9 ± 3.6 μM, while the activity of LEC rat liver microsomes increased with increasing Fe(II) up to 500 μM with a K0.5 value of 64.4 ± 8.1 μM. The K0.5 values for Fe(II)-dependent ATPase activity of spleen OTG-microsomes were nearly identical at 59.3 μM in the Wistar rat and 63.7 μM in the LEC rats with a similar level of activity at each Fe(II) concentration in both strains of animals. These results indicated that there are two types of Fe(II)-dependent ATPase with different Fe(II) sensitivity, a high sensitive (H) and a low sensitive (L) type, and that the H-type activity was specific to the liver. The H-type activity was, however, deficient in the liver of LEC rats that accumulate copper and iron in hepatocytes as a result of mutations in the Wilson's disease protein (WNDP). On the basis of these results, together with the similarity in optimal conditions required for full activity of the enzyme, we conclude that the Fe(II)-dependent ATPase (H-type) and WNDP may be identical.
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