[Kinetics of Ca 2+ or Mg 2+ activated ATPase from lymphocyte plasma membranes].
The kinetic study of the C2+ ATPase activity of lymphocyte plasma memebranes allowed some properties of this enzyme to be evidenced. The Ca2+-activated hydrolysis of ATP is independent of a non-specific alkaline phosphatase. The substrate of the ATPase activity is the chelate Ca2+- ATP. Mg2+ may substitute for Ca2+ both as chelating ion and as activating ion. Several results suggest that we have only one ATPase, activated either by Ca2+-, or by Mg2+ with less efficiency; both chelates hve the same Km; pH values for maximum activity and transition temperatures are identical; the effects of free ions are also the same, activation at low concentration and inhibition at high concentration.
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000469:Alkaline Phosphatase / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology*; D002462:Cell Membrane / Q000201:enzymology; D004789:Enzyme Activation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008214:Lymphocytes / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology*; D013696:Temperature; D013816:Thermodynamics
D000469:Alkaline Phosphatase; D000251:Adenosine Triphosphatases; D008274:Magnesium; D002118:Calcium
Etude cinétique de l'activité ATPase activée par Ca2+ ou Mg2+ des membranes plasmiques lymphocytaires