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Effects of ethanol and other alkanols on the kinetics and the activation parameters of thermal death in Saccharomyces cerevisiae
Author(s) -
Leão Cecília,
Van Uden N.
Publication year - 1982
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260240711
Subject(s) - chemistry , thermodynamics , entropy of activation , partition coefficient , enthalpy , kinetics , entropy (arrow of time) , aqueous solution , ethanol , reaction rate constant , chromatography , organic chemistry , physics , quantum mechanics
Ethanol, isopropanol, propanol, and butanol enhanced thermal death in Saccharomyces cerevisiae by increasing ΔS‡, the entropy of activation of thermal death while Δ H ‡, the enthalpy of activation, was not significantly affected. The relation between Δ S ‡ and alkanol concentration was linear with a different slope for each alkanol: Δ S ‡ X = Δ S ‡ 0 + C A E X , where X is the alkanol concentration and C A E the entropy coefficient for the aqueous phase defined as increase in entropy of activation per unit concentrations of the alkanol. C A E was correlated with the lipid‐buffer partition coefficients of the alkanols while C M E , the entropy coefficient for the lipid phase, was nearly identical for the four alkanol and averaged 37.6 entropy units per mole of alkanol per kilogram of membrane. As predicted by these results, the specific death rates ( K d ) at constant temperature were an exponential function of the alkanol concentration and behaved in agreement with the following equation: In K X d = In K 0 d + ( C A E / R ) X , where R is the gas constant. It was concluded that the alkanols enhanced thermal death through nonspecific action on membrane structure.