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Effect of divalent cations on Na + ,K + ‐ATPase obtained from human placenta
Author(s) -
Zolese G.,
Staffolani R.,
Mazzanti L.,
Gratton E.
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)81437-5
Subject(s) - chemistry , divalent , quenching (fluorescence) , vesicle , phosphatidylcholine , circular dichroism , phospholipid , acrylamide , atpase , crystallography , biochemistry , biophysics , enzyme , fluorescence , membrane , biology , monomer , organic chemistry , physics , polymer , quantum mechanics
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, Ca 2+ and Mg 2+ increased the activity, the effect being more pronounced after preincubation of the protein with Mg 2+ . CD data suggest that this activity increase may be linked to a change in the secondary structure of the ATPase, in particular β‐turn, β‐sheet and random coil. Acrylamide quenching studies suggest that ions could primarily interact with phospholipid head groups, but not directly with the protein.