Effect of divalent cations on Na+,K(+)-ATPase obtained from human placenta.
- Author(s): Zolese, G
- Staffolani, R
- Mazzanti, L
- Gratton, E
- et al.
Published Web Locationhttps://doi.org/10.1016/0014-5793(93)81437-5
Circular dichroism (CD) and acrylamide quenching studies of Na+,K(+)-ATPase from human placenta showed that its incorporation into phosphatidylcholine vesicles increased the enzymic activity by 55%. Moreover, both with the purified and the vesicle-reconstituted protein, Ca2+ and Mg2+ increased the activity, the effect being more pronounced after preincubation of the protein with Mg2+. CD data suggest that this activity increase may be linked to a change in the secondary structure of the ATPase, in particular beta-turn, beta-sheet and random coil. Acrylamide quenching studies suggest that ions could primarily interact with phospholipid head groups, but not directly with the protein.