John K. Raison

The influence of temperature-induced phase changes on the kinetics of respiratory and other membrane-associated enzyme systems

Temperature-mediated changes in the kinetics of enzyme catalysed reactions can be due to effects on a number of different parameters. If the change in temperature does not (a) inactivate the enzyme, (b) alter the affinity of the enzyme for the substrate, an activator or an inhibitor or (c) alter the pH function of the reaction components, the velocity of enzyme catalysed reactions increases with increasing temperature. The relationship between the velocity of reaction and temperature can be expressed either as the activation energy (E) or the temperature coefficient (Q10). Both expressions can be derived from the empirical Arrhenius equation relating the velocity of reaction and temperature

A temperature-induced transition in mitochondrial oxidation: Contrasts between cold and warm-blooded animals

\frac{\alpha \ln k}{\alpha T}=\frac{E}{R{{T}^{2}}}

Membrane lipid fluidity and its effect on the activation energy of membrane-associated enzymes

(1) where k is the reaction velocity constant, R the gas constant, T the absolute temperature and E a constant, subsequently called the activation energy (also written as A or μ.). Integration of equation (1) gives

The influence of thyroid hormones on the structure and function of mitochondrial membranes

\ln \frac{{{k}_{2}}}{{{k}_{1}}}=\frac{E}{R}\left( \frac{1}{{{T}_{1}}}-\frac{1}{{{T}_{2}}} \right)

Two temperature-induced changes in mitochondrial membranes detected by spin labelling and enzyme kinetics

(2) from which it can be seen that the value for E can be obtained from the slope of the straight line when logk is plotted against 1/T