An osmolyte effect on the heat capacity change for protein folding.


We have carried out a differential scanning calorimetry study into the pH effect on the thermal denaturation of ribonuclease A at several concentrations of the osmolyte sarcosine. In order to properly analyze these data, we have elaborated the thermodynamic theory of the linkage between temperature, cosolvent, and pH effects. The denaturation heat capacity increases with sarcosine concentration. The effects of temperature and sarcosine concentration on the denaturation enthalpy and entropy values are well described by convergence equations, with convergence temperatures of around 100 degrees C for the enthalpy and around 112 degrees C for the entropy; we suggest that these effects might be related to a solvent-induced alteration of the apolar-group-hydration contribution to the folding thermodynamics. From our data, we estimate that about 70 extra molecules of water are thermodynamically bound upon ribonuclease denaturation in diluted aqueous solutions of sarcosine; this number is 6-9 times smaller than that predicted on the basis of the following two premises: (a) the osmolyte is strongly excluded from the surface of both the native and the denatured protein and (b) the denatured state is a fully solvated chain. We suggest that at least one of these two premises does not hold. We briefly comment on the potential use of cosolvent effects on thermal denaturation to evaluate the degree of hydration of denatured proteins (thus providing an independent measure of the consequence of their possible residual structure) and, also, on the possibility of finding substances that are more efficient protein stabilizers than known osmolytes are. Study holds ProTherm entries: 5074, 5075 Extra Details: osmolyte effect; heat capacity change; protein folding

Submission Details


Submitter: Connie Wang

Submission Date: April 24, 2018, 8:28 p.m.

Version: 1

Publication Details
Plaza del Pino IM;Sanchez-Ruiz JM,Biochemistry (1995) An osmolyte effect on the heat capacity change for protein folding. PMID:7542026
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Ribonuclease pancreatic P61824 RNAS1_BISBI
100.0 Ribonuclease pancreatic P61823 RNAS1_BOVIN
96.8 Ribonuclease pancreatic P67926 RNAS1_CAPHI
96.8 Ribonuclease pancreatic P67927 RNAS1_SHEEP
95.2 Ribonuclease pancreatic P00657 RNAS1_BUBBU
96.0 Ribonuclease pancreatic P07847 RNAS1_AEPME
93.5 Ribonuclease pancreatic P07848 RNAS1_EUDTH
95.2 Ribonuclease pancreatic P00660 RNAS1_CONTA
92.7 Ribonuclease pancreatic P00668 RNAS1_ANTAM
90.3 Ribonuclease pancreatic P00662 RNAS1_GIRCA
96.0 Ribonuclease pancreatic Q29606 RNAS1_ORYLE