A new intrinsic thermal parameter for enzymes reveals true temperature optima. VOLUME 279 (2004) PAGES 20717-20722
摘要
PAGE 20720: Table I: It has become apparent to us that incorrect units were used for the fitting of experimental data to the “Equilibrium Model” and that the values for ΔGcat‡, ΔGinact‡, ΔHeq, and Teq published in this paper are therefore incorrect; a corrected Table I is shown below. The main conclusion of the paper is unaffected, namely that “The results and their analysis indicate that the experimental velocity data as a function of temperature can be described by the Equilibrium Model, suggesting Keq as an intrinsic, temperature-dependent property of enzymes, and supporting the hypothesis that these enzymes possess a third thermal parameter (Teq), alongside the Arrhenius activation energy and the activation energy for thermal stability.”TABLE ONESummary of experimentally determined thermodynamic parametersEnzymeOriginGrowth temp.ToptTeqΔGcat‡ΔGinact‡ΔHeq°C°C°CkJ·mol−1kJ·mol−1kJ·mol−1Aryl-acylamidaseP. fluorescens2538367492133β-LactamaseB. cereus3053536994146Acid phosphataseWheat germ15-25aSpring germination temperatures.66637995133Adenosine deaminaseBovine spleen3962566599101Alkaline phosphataseBovine intestine396860579786a Spring germination temperatures. Open table in a new tab However, based on the original table we stated: “For β-lactamase and adenosine deaminase, the difference between Topt and Teq is greater than for the other enzymes;...” This statement no longer applies. In addition, as a result of the corrected values, the statement that “Topt will be close in value to Teq and always smaller” should read: “Topt will almost always be close in value to Teq but may be smaller or larger, depending on the relative values of ΔGcat‡ and ΔHeq.”