Membrane Enzymes: Artifacts in Arrhenius Plots Due to Temperature Dependence of Substrate-Binding Affinity

• Published in: Science (American Association for the Advancement of Science) Vol. 199; no. 4331; pp. 902 - 904
• Main Authors: Silvius, John R., Read, Brian D., McElhaney, Ronald N.
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 24-02-1978
• Subjects: Acholeplasma laidlawii; Acholeplasma laidlawii - enzymology; Adenosine Triphosphatases - metabolism; Adenosine Triphosphate - metabolism; B lymphocytes; Enzyme substrates; Enzymes; Fatty acids; Fatty Acids - pharmacology; Kinetics; Magnesium - metabolism; Mathematical constants; Membrane fluidity; Membrane Proteins - metabolism; Membranes - enzymology; P branes; String theory; Temperature; Temperature dependence; Thermodynamics
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.146257

For the membrane sodium-stimulated magnesium-adenosinetriphosphatase of Acholeplasma laidlawii B both the V$_{max}$ and K$_{m}$ values in the Michaelis equation vary strongly with temperature. Simulations of Arrhenius plots show that an enzyme with a temperature-dependent K$_{m}$ can yield a variety of Arrhenius plot artifacts, most notably erroneous "breaks," if activity is assayed at a fixed substrate concentration.