6nw4

Publication Abstract from PubMed

Temperature influences the reaction kinetics and evolvability of all enzymes. To understand how evolution shapes the thermodynamic drivers of catalysis, we optimized the modest activity of a computationally designed enzyme for an elementary proton-transfer reaction by nearly 4 orders of magnitude over 9 rounds of mutagenesis and screening. As theorized for primordial enzymes, the catalytic effects of the original design were almost entirely enthalpic in origin, as were the rate enhancements achieved by laboratory evolution. However, the large reductions in DeltaH() were partially offset by a decrease in TDeltaS() and unexpectedly accompanied by a negative activation heat capacity, signaling strong adaptation to the operating temperature. These findings echo reports of temperature-dependent activation parameters for highly evolved natural enzymes and are relevant to explanations of enzymatic catalysis and adaptation to changing thermal environments.

Emergence of a Negative Activation Heat Capacity during Evolution of a Designed Enzyme.,Bunzel HA, Kries H, Marchetti L, Zeymer C, Mittl PRE, Mulholland AJ, Hilvert D J Am Chem Soc. 2019 Jul 19. doi: 10.1021/jacs.9b02731. PMID:31282667^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.