Linked Life Data

8393940

Source:http://linkedlifedata.com/resource/pubmed/id/8393940

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1993-9-9
pubmed:abstractText
The enthalpy of hydration of polar and non-polar groups upon protein unfolding has been estimated for four globular proteins in the temperature range 5 to 125 degrees C, using structural information on the groups in these proteins exposed to water in the native and unfolded states and volume-corrected calorimetric information on the enthalpy and heat capacity of transfer into water of various model compounds. It has been shown that the enthalpy of hydration of polar groups greatly exceeds the enthalpy of hydration of non-polar groups. At low temperatures both these enthalpies are negative and change in opposite direction with increasing temperature. Subtracting the total enthalpy of hydration of polar and non-polar groups from the calorimetrically determined enthalpy of protein unfolding, the total enthalpy of internal interactions maintaining the native protein structure has been determined. Using thermodynamic information on the sublimation of organic crystals, the total enthalpy was divided into two components: one associated with the interactions between the non-polar groups (van der Waals interaction) and the rest associated with the interactions between polar groups (hydrogen bonding). This made it possible to estimate the overall enthalpies of disruption of contacts between the polar groups with their exposure to water and between the non-polar groups with their exposure to water. It appears that these enthalpies have opposite signs in the temperature range considered and change in opposite directions with increasing temperature. The enthalpy of transfer of non-polar groups from the protein interior into water is negative below 25 degrees C and positive above. The enthalpy of transfer of polar groups from the protein interior into water is positive at low temperatures and becomes negative at higher temperatures. Over the considered temperature range, however, the enthalpy of transfer of non-polar groups dominates. This results in a positive enthalpy of protein unfolding at elevated temperatures. The opposite sign and temperature dependence of the specific values of these two enthalpies for the considered proteins explains the experimentally observed convergence of the specific enthalpies of globular protein unfolding at about 130 degrees C.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0022-2836
pubmed:author
pubmed:issnType
Print
pubmed:day
20
pubmed:volume
232
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
639-59
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Contribution of hydration to protein folding thermodynamics. I. The enthalpy of hydration.
pubmed:affiliation
Department of Biology and Biocalorimetric Center, Johns Hopkins University, Baltimore, MD 21218.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.