Calorimetric study of the heat and cold denaturation of beta-lactoglobulin.


Abstract

Temperature-induced changes of the states of beta-lactoglobulin have been studied calorimetrically. In the presence of a high concentration of urea this protein shows not only heat but also cold denaturation. Its heat denaturation is approximated very closely by a two-state transition, while the cold denaturation deviates considerably from the two-state transition and this deviation increases as the temperature decreases. The heat effect of cold denaturation is opposite in sign to that of heat denaturation and is noticeably larger in magnitude. This difference in magnitude is caused by the temperature-dependent negative heat effect of additional binding of urea to the polypeptide chain of the protein upon its unfolding, which decreases the positive enthalpy of heat denaturation and increases the negative enthalpy of cold denaturation. The binding of urea considerably increases the partial heat capacity of the protein, especially in the denatured state. However, when corrected for the heat capacity effect of urea binding, the partial heat capacity of the denatured protein is close in magnitude to that expected for the unfolded polypeptide chain in aqueous solution without urea but only for temperatures below 10 degrees C. At higher temperatures, the heat capacity of the denatured protein is lower than that expected for the unfolded polypeptide chain. It appears that at temperatures above 10 degrees C not all the surface of the beta-lactoglobulin polypeptide chain is exposed to the solvent, even in the presence of 6 M urea; i.e., the denatured protein is not completely unfolded and unfolds only at temperatures lower than 10 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS) Study holds ProTherm entries: 2783, 2784, 2785 Extra Details: measurement was made in the presence of 0.1M KCl/HCl beta-lactoglobulin; heat and cold denaturation; calorimetric study;,partial heat capacity; protein unfolding

Submission Details

ID: WuNKpKu5

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:19 p.m.

Version: 1

Publication Details
Griko YV;Privalov PL,Biochemistry (1992) Calorimetric study of the heat and cold denaturation of beta-lactoglobulin. PMID:1390668
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 PDB Entries

Structure ID Release Date Resolution Structure Title
4CK4 2013-12-27T00:00:00+0000 1.12 Ovine beta-Lactoglobulin at Atomic Resolution
4NLI 2013-11-14T00:00:00+0000 1.9 Crystal structure of sheep beta-lactoglobulin (space group P3121)
4NLJ 2013-11-14T00:00:00+0000 1.4 Crystal structure of sheep beta-lactoglobulin (space group P1)
6T44 2019-10-12T00:00:00+0000 2.0 Ovine lactoglobulin complex with decanol
4OMW 2014-01-27T00:00:00+0000 2.3 Crystal structure of goat beta-lactoglobulin (orthorhombic form)
4OMX 2014-01-27T00:00:00+0000 2.3 Crystal structure of goat beta-lactoglobulin (trigonal form)
4TLJ 2014-05-30T00:00:00+0000 1.17 Ultra-high resolution crystal structure of caprine Beta-lactoglobulin
4Y0S 2015-02-06T00:00:00+0000 1.9 Goat beta-lactoglobulin complex with pramocaine (GLG-PRM)
7LWC 2021-02-28T00:00:00+0000 3.0 Goat beta-lactoglobulin mutant Q59A
1B0O 1998-11-11T00:00:00+0000 2.5 BOVINE BETA-LACTOGLOBULIN COMPLEXED WITH PALMITATE, LATTICE Z

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Beta-lactoglobulin P02754 LACB_BOVIN
98.8 Beta-lactoglobulin P02755 LACB_BUBBU
96.3 Beta-lactoglobulin P02756 LACB_CAPHI
95.7 Beta-lactoglobulin P67976 LACB_SHEEP
95.7 Beta-lactoglobulin P67975 LACB_OVIMU