Platelet AMP deaminase. Purification and kinetic studies.
AMP deaminase has been purified to homogeneity from human platelets by phosphocellulose chromatography. Kinetic studies showed sigmoidal behavior as a function of AMP concentration with the midpoint of the saturation curve (S0.5) at 3.5 and 4.0 mM in NaCl and KCl, respectively, at pH 6.5. Activation by saturating ATP converted the velocity versus substrate plot to hyperbolic with a Michaelis constant of 1.2 mM and the same maximum velocity in either salt. Addition of increasing concentrations of GTP in the presence of NaCl led to activation followed by inhibition whereas GTP in the presence of KCl gave inhibition with no apparent activation.
D000659:AMP Deaminase / Q000097:blood* / Q000302:isolation & purification; D001792:Blood Platelets / Q000201:enzymology*; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D008433:Mathematics; D008970:Molecular Weight; D009709:Nucleotide Deaminases / Q000097:blood*; D011189:Potassium Chloride / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology
D012965:Sodium Chloride; D011189:Potassium Chloride; D006160:Guanosine Triphosphate; D009709:Nucleotide Deaminases; D000659:AMP Deaminase