2 research outputs found
Calculation of the relative metastabilities of proteins in subcellular compartments of Saccharomyces cerevisiae
[abridged] Background: The distribution of chemical species in an open system
at metastable equilibrium can be expressed as a function of environmental
variables which can include temperature, oxidation-reduction potential and
others. Calculations of metastable equilibrium for various model systems were
used to characterize chemical transformations among proteins and groups of
proteins found in different compartments of yeast cells.
Results: With increasing oxygen fugacity, the relative metastability fields
of model proteins for major subcellular compartments go as mitochondrion,
endoplasmic reticulum, cytoplasm, nucleus. In a metastable equilibrium setting
at relatively high oxygen fugacity, proteins making up actin are predominant,
but those constituting the microtubule occur with a low chemical activity. A
reaction sequence involving the microtubule and spindle pole proteins was
predicted by combining the known intercompartmental interactions with a
hypothetical program of oxygen fugacity changes in the local environment. In
further calculations, the most-abundant proteins within compartments generally
occur in relative abundances that only weakly correspond to a metastable
equilibrium distribution. However, physiological populations of proteins that
form complexes often show an overall positive or negative correlation with the
relative abundances of proteins in metastable assemblages.
Conclusions: This study explored the outlines of a thermodynamic description
of chemical transformations among interacting proteins in yeast cells. The
results suggest that these methods can be used to measure the degree of
departure of a natural biochemical process or population from a local minimum
in Gibbs energy.Comment: 32 pages, 7 figures; supporting information is available at
http://www.chnosz.net/yeas