The entropy cost of protein association.
The temperature induced unfolding/dissociation of the dimeric subtilisin inhibitor from Streptomyces and its mutant D83C having an S-S crosslink between the subunits has been studied calorimetrically. Comparison of the entropies measured at different concentrations of dimer showed that the entropy cost of crosslinking is small. Its value at the standard concentration of 1 M is of the order of -(5+/-4) cal/K.mol, i.e. it is more than one order of magnitude smaller than the values of translational entropies calculated on the base of statistical thermodynamics, using in particular the Sackur-Tetrode equation, and is close to the cratic entropy value suggested by classical mixing theory.
Tamura
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Graduate School of Science and Technology, Kobe University, Rokkodai, Kobe 657, Nada, Japan.
Privalov
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PL
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002151:Calorimetry; D002942:Circular Dichroism; D019281:Dimerization; D019277:Entropy; D006358:Hot Temperature; D009682:Magnetic Resonance Spectroscopy; D017510:Protein Folding; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D013302:Streptomyces / Q000737:chemistry / Q000235:genetics
D001426:Bacterial Proteins; D011506:Proteins; C018150:subtilisin inhibitor protein, Streptomyces