Biphasic denaturation of human albumin due to ligand redistribution during unfolding.


Abstract

Denaturation of defatted human albumin monomer, monitored by differential scanning calorimetry, is monophasic as reflected by the single, resulting endotherm. With low levels of various ligands, biphasic or monophasic unfolding processes are manifested as bimodal or unimodal thermograms, respectively. The greater the affinity of native protein for ligand, the greater is the tendency for biphasic denaturation. We propose that such a biphasic unfolding process arises from a substantial increase in stability (transition temperature) of remaining native protein during denaturation. This increase in stability derives from the free energy of ligand binding becoming more negative due to the release of high affinity ligand by unfolding protein. The tendency for biphasic denaturation is greatest at low (subsaturating) levels of ligand where greatest increases in stability occur. Biphasic unfolding arising from such ligand redistribution results from denaturation of different kinds of protein molecules, ligand-poor and ligand-rich species, and not from sequential unfolding of domains within the same molecule. Differentiating between these two mechanisms is necessary for the correct interpretation of biphasic denaturation data. Furthermore, biphasic unfolding due to ligand redistribution occurs independently of the means used to effect denaturation. The maximum increase in stability due to ligand binding relative to the stability of defatted albumin monomer alone occurs with the intermediate affinity ligand octanoate (22 degrees C) and not with the high affinity ligand hexadecanoate (15 degrees C). This indicates a much greater affinity of denatured albumin for hexadecanoate since increase in stability derives from the difference between free energy of ligand binding to folded and unfolded protein forms. Study holds ProTherm entries: 5141 Extra Details: unimodal thermograms; biphasic denaturation; ligand binding;,intermediate affinity

Submission Details

ID: 64EY4cG94

Submitter: Connie Wang

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

Version: 1

Publication Details
Shrake A;Ross PD,J. Biol. Chem. (1988) Biphasic denaturation of human albumin due to ligand redistribution during unfolding. PMID:3170588
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
1AO6 1997-07-18T00:00:00+0000 2.5 CRYSTAL STRUCTURE OF HUMAN SERUM ALBUMIN
1BJ5 1998-07-02T00:00:00+0000 2.5 HUMAN SERUM ALBUMIN COMPLEXED WITH MYRISTIC ACID
1BKE 1998-07-06T00:00:00+0000 3.15 HUMAN SERUM ALBUMIN IN A COMPLEX WITH MYRISTIC ACID AND TRI-IODOBENZOIC ACID
1BM0 1998-07-28T00:00:00+0000 2.5 CRYSTAL STRUCTURE OF HUMAN SERUM ALBUMIN
1E78 2000-08-25T00:00:00+0000 2.6 Crystal structure of human serum albumin
1E7A 2000-08-26T00:00:00+0000 2.2 Crystal structure of human serum albumin complexed with the general anesthetic propofol
1E7B 2000-08-26T00:00:00+0000 2.38 Crystal structure of human serum albumin complexed with the general anesthetic halothane
1E7C 2000-08-26T00:00:00+0000 2.4 HUMAN SERUM ALBUMIN COMPLEXED WITH MYRISTIC ACID and the general anesthetic halothane
1E7E 2000-08-29T00:00:00+0000 2.5 HUMAN SERUM ALBUMIN COMPLEXED WITH DECANOIC ACID (CAPRIC ACID)
1E7F 2000-08-29T00:00:00+0000 2.43 HUMAN SERUM ALBUMIN COMPLEXED WITH DODECANOIC ACID (LAURIC ACID)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
93.7 Serum albumin Q28522 ALBU_MACMU
93.7 Serum albumin A2V9Z4 ALBU_MACFA
98.5 SERUM ALBUMIN Q5NVH5 ALBU_PONAB
100.0 SERUM ALBUMIN P02768 ALBU_HUMAN