Study of immobilized yeast, Saccharomyces cerevisiae, using flow microcalorimetry.

When immobilized yeast was exposed to nutrients, the resulting heat effect (dQ/dt; J sec-1) increased exponentially with a doubling time (t2) of 2.2±0.3hr. The half life (dQ/dt) under non-growing conditions with sucrose as substrate was 84hr. The kinetics of the transformation of a series of sugars were characterised. The Michaelis constant (Km) and maximal heat effect, (dQ/dt)max, were determined using two common enzyme kinetics linearization plots. The shapes of the Eadie plots for some sugars are discussed in terms of currently proposed mechanisms of their uptake