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Evidence For An Ambidirectional Magnesium-Activated, Sodium-Potassium Dependent Adenosine Triphosphatase, John Dale Hempel

Master's Theses

Controversy exists as to whether the Na-K ATPases of euryhaline fishes are the same enzyme.This study demonstrates that the phosphorylated enzyme from gills of Fundulus heteroclitus adapted to freshwater and salt water migrate to the same position in SDS polyacrylamide gels. Similar behavior of the enzyme from both sources in different ionic media is also shown. Additionally, the possible ability or the enzyme to couple an osmoregulatory influx to an excretory efflux in freshwater fish is demonstrated. The term "ambidirectional" is proposed for this enzyme, and its place in certain membrane models is discussed.