Heat capacity measurements from 10 to 300 K and derived thermodynamic functions of lyophilized cells of Saccharomyces cerevisiae including the absolute entropy and the entropy of formation at 298.15 K

Heat capacity measurements using an adiabatic calorimeter have been made from 7 to 310 K on a carefully prepared specimen of lyophilized cells of Saccharomyces cerevisiae (yeast). From these measurements, a value of 1.304 J K-1 g(-1) has been obtained for the absolute entropy of yeast cells at 298.15 K, based on third-law calculations. Chemical analysis of the cells yielded an empirical chemical formula for the cellular stoichiometry, which has been expressed as an ion-containing carbon mole, (ICC-mol). A value of 34.167 J K-1.ICC-mol(-1) for the absolute entropy of this mass of cells and of -151.46 J K-1.ICC-mol(-1) for the entropy of formation has been calculated. The absolute entropy/g of the yeast cells falls within the range of those for simple biological molecules like sugars and amino acids and more complex biopolymers like proteins. We conclude that the thermodynamic effect of cellular organization in the dried cells is negligible. (C) 1997 Elsevier Science B.V.