The boost in enzymatic costs with 5-HT Receptor pathway inhibitor temperature up to an optimum temperature (T-opt) is widely attributed to classical Arrhenius behavior, using the lower in enzymatic costs above T-opt ascribed to protein denaturation and/or aggregation. This account persists despite numerous investigators noting that denaturation is inadequate to describe the decline in enzymatic rates above T-opt. Right here we show that it is the modify in heat capacity linked with enzyme catalysis (Delta C-p(double dagger)) and its effect on the temperature dependence of Delta G(double dagger) that determines the temperature dependence of enzyme activity. Through mutagenesis, we show the T-opt of an enzyme Interleukin-4 receptor is correlated with Delta C-p(double dagger) and that improvements to Delta C-p(double dagger) are adequate to alter T-opt with no affecting the catalytic fee. Furthermore, using X-ray crystallography and molecular dynamics simulations we reveal the molecular facts underpinning these adjustments in Delta C-p(double dagger). The influence of Delta C-p(double dagger) on enzymatic charges has implications to the temperature dependence of selleck catalog biological prices from enzymes to ecosystems.