title: Membrane enzymes: artifacts in Arrhenius plots due to temperature dependence of substrate-binding affinity.
abstract: For the membrane sodium-stimulated magnesium-adenosinetriphosphatase of Acholeplasma laidlawii B both the Vmax and Km values in the Michaelis equation very strongly with temperature. Simulations of Arrhenius plots show that an enzyme with a temperature-dependent Km can yield a variety of Arrhenius plot artifacts, most notably erroneous "breaks," if activity is assayed at a fixed substrate concentration.
mesh_terms: D000128:Acholeplasma laidlawii / Q000201:enzymology; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D005227:Fatty Acids / Q000494:pharmacology; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008566:Membranes / Q000201:enzymology*; D013696:Temperature; D013816:Thermodynamics
chemical_list: D005227:Fatty Acids; D008565:Membrane Proteins; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D008274:Magnesium