Dimethyl sulfoxide: a possible effect on the interconversion of phosphorylated forms of Na+,K(+)-ATPase.
Purified Na+,K(+)-ATPase from kidney outer medulla was phosphorylated by Pi in a reaction synergistically stimulated by Mg2+, when 40% (v/v) dimethyl sulfoxide was added to the assay medium. The phosphoenzyme formed at this solvent concentration was able to synthesize ATP even in the presence of Mg2+, because hydrolysis was impaired. ATP in equilibrium [32P]Pi exchange was also inhibited, indicating that partial reactions in the forward direction were blocked by the solvent. In 40% (v/v) dimethyl sulfoxide the enzyme's affinity for ADP decreased, in comparison with the values observed in purely aqueous medium. Addition of K+, which accelerated dephosphorylation of Na+,K(+)-ATPase in a totally water medium, partially reversed the inhibition of hydrolysis that was observed in the presence of dimethyl sulfoxide.
de Moraes
V L
VL
Departamento de Bioquímica, ICB, Universidade Federal de Rio de Janeiro, Brasil.
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D006593:Hexokinase / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000201:enzymology; D008274:Magnesium / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011188:Potassium / Q000494:pharmacology; D012756:Sheep; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014867:Water
D010750:Phosphoproteins; D014867:Water; D000255:Adenosine Triphosphate; D006593:Hexokinase; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium; D011188:Potassium; D004121:Dimethyl Sulfoxide