Changes in protein hydration during thermal denaturation of rnase A

Michael G. Fried, Jennifer L. Bromberg

Research output: Contribution to journalArticlepeer-review


We have used the osmotic stress technique to measure the difference in the number of water molecules thermodynamically associated with ribonuciease A in its native and heat-denatured states. For reversible denaturation in 30 mM glycine, pH 2.2, five osmolytes (betaine, glycerol, sarcosine, sorbitol and triethylene glycol) gave apparent water stoichiometry differences (δnw) in the range 37 < δnw < 153. If each bound water molecule occupies 8-10Å2 of solvent accessible protein surface, these stoichiometries indicate that the change in solvent accessible surface area (δ5ASA) is < 1530 Å2, Denaturation in the presence of lOmM 2-mercaptoethanol gave only slightly greater values, indicating that disulfide crosslinking has little effect on the change of solvent exposure accompanying denaturation. This experimental estimate of δUASA is considerably smaller than theoretical values reported in the literature. We suggest that current models of the denatured state of ribonuciease A overestimate its soivent exposure.

Original languageEnglish
Pages (from-to)A1436
JournalFASEB Journal
Issue number8
StatePublished - 1998

ASJC Scopus subject areas

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics


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