pH‐Dependent Change in the Oligomeric Structure of the Solubilized Na⁺/K⁺‐ATPase

Oligomeric Structure of Solubilized Na+/K+ ‐ATPase Linked to E1/E2 Conformation

“…Therefore, the interconversion of oligomeric structure between D and P is essential for enzymatic function. The molecular structure of Na + /K + ‐ATPase in the membrane is consequently thought to be as follows: the E 1 and E 2 conformations correspond to a loosely associated diprotomer and a tightly associated diprotomer, respectively; two‐dimensional crystals of the membrane‐bound enzyme grown at pH 4.8 in sodium citrate buffer 20 can be expected to reveal a three‐dimensional structure of the enzyme in E 2 ‐conformation for reasons described elsewhere 12 …”

“…5). We presented a paper on this subject elsewhere in this volume 12 . Therefore, it was concluded that KCl and NaCl increased the content of D and P, respectively, and that this alteration was followed by a change in fluorescence intensity that was proportional to the content in the solubilized enzyme.…”

“…The minor component of H was thought to be an associate and/or aggregate because its M r values were much higher than those of the major components and it had a nonstoichiometric molar ratio of α:β. The elution pattern with the three peaks of H, D, and P were obtained when chromatography was performed at around 0°C, although the relative contents of D to P were altered depending on the kind of ligand included in the elution buffer at neutral pH and on the pH value of the elution buffer 12 . The D and P that emerged from the column contained about 15 mol of phospholipid in common, and 150 and 200 mol of C 12 E 8 formed part of D and P, respectively, per αβ‐protomeric unit 7,8 .…”

“…M NaCl at 0°C and eluted with the same elution buffer. Chromatography allowed us to estimate the relative contents of D and P of the solubilized enzyme from the areas under the two resulting protein peaks of D and P 12 . With increasing ATP concentrations from 0 to more than 1 mM, the content of P decreased from 56 to 26%, whereas that of D increased from 37 to 64%.…”

Mecanismos de dissociação das subunidades alfa e Beta da Na,K-ATPase por agentes químicos e físicos: comparação entre a enzima solubilizada e reconstituída em lipossomos

“…(Thoengs e Kobayashi et al, 1997;Linnertz et al, 1997Linnertz et al, , 1998Antolovic et al, 1999;Santos e Ciancaglini, 2003, Costa et al, 2003, Rigos et al, 2006, ou ainda na forma de um tetraprotômero (αβ)4 (Mahaney et al, 1990;Tsuda et al, 1998;Yokoyama et al, 1999;Taniguchi et al, 2001;Donnet et al, 2001).…”