Re: state variables

Arnold Neumaier wrote: 
My description above was for proteins in solution, considered as a
fluid. Only on this level is local equilibrium appropriate. But on this
level, one cannot use the model of an isotropic fluid, which leads to
Newtonian behavior. Macromolecules are strongly non-Newtonian.

If you are thinking about physiological conditions, things are worse still. Many proteins do not function in solution, but are embedded in membranes with different conditions on each side (e.g. ion pumps), or bound in complexes with hundreds of proteins and other molecules (e.g. ribosomes, chromosomes), or both.

Also, the thermodynamic approximation may not be very good. Some molecules must exist in exact numbers (chromosomes again, one extra or one missing is bad news), and a *single* molecule of some proteins (e.g. ricin) will kill a cell.

Ralph Hartley

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