The 28-111 disulfide bond constrains the alpha-lactalbumin molten globule and weakens its cooperativity of folding.


Abstract

Our aim is to determine whether the disulfide bonds of alpha-lactalbumin account for the lack of cooperative folding behavior reported for some molten globule variants, in contrast to the highly cooperative folding reported for the pH 4 molten globule of apomyoglobin. Two different alpha-lactalbumin genetic constructs are studied: [28-111], which has a single disulfide bond connecting two segments of the alpha-helix domain, and [all-Ala], which has no disulfide bonds. The superposition test used earlier to probe for cooperative folding of the apomyoglobin molten globule is used to determine whether there is an important difference in folding cooperativity between the molten globules of [28-111] and [all-Ala]. The [all-Ala] construct behaves in the same manner as the apomyoglobin molten globule: its folding satisfies the superposition test in the three sets of anion conditions studied, and anions stabilize it against urea unfolding. The [28-111] construct behaves differently in both respects: the folding of its molten globule does not satisfy the superposition test in two of the three sets of anion conditions, and anions barely affect its stability. The 28-111 disulfide bond stabilizes the molten globule substantially, as expected from earlier work. Comparison of the unfolding transition curves monitored by circular dichroism also demonstrates that [28-111] folds in a less cooperative manner than [all-Ala]: the unfolding curve of [28-111] is significantly broader. Moreover, the unfolding curves indicate that [28-111] has a lower helix content than [all-Ala]. Consequently, the 28-111 bond constrains the folding behavior of the molten globule and weakens its cooperativity of folding. Study holds ProTherm entries: 13168, 13169, 13170, 13171, 13172, 13173 Extra Details: Alpha-lactalbumin(all-Ala) disulfide bonds; alpha-lactalbumin; molten globule variants;,urea unfolding; circular dichroism

Submission Details

ID: Ch7TpCdy

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:45 p.m.

Version: 1

Publication Details
Luo Y;Baldwin RL,Proc. Natl. Acad. Sci. U.S.A. (1999) The 28-111 disulfide bond constrains the alpha-lactalbumin molten globule and weakens its cooperativity of folding. PMID:10500168
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
1CB3 1999-06-08 LOCAL INTERACTIONS DRIVE THE FORMATION OF NON-NATIVE STRUCTURE IN THE DENATURED STATE OF HUMAN ALPHA-LACTALBUMIN: A HIGH RESOLUTION STRUCTURAL CHARACTERIZATION OF A PEPTIDE MODEL IN AQUEOUS SOLUTION
1B9O 1999-03-31 1.15 HUMAN ALPHA-LACTALBUMIN, LOW TEMPERATURE FORM
3B0O 2012-06-13 1.61 Crystal structure of alpha-lactalbumin
1ALC 1989-10-15 1.7 REFINED STRUCTURE OF BABOON ALPHA-LACTALBUMIN AT 1.7 ANGSTROMS RESOLUTION. COMPARISON WITH C-TYPE LYSOZYME
1HML 1995-01-26 1.7 ALPHA_LACTALBUMIN POSSESSES A DISTINCT ZINC BINDING SITE
1A4V 1999-04-27 1.8 ALPHA-LACTALBUMIN
3B0I 2012-06-13 1.8 Crystal structure of recombinant human alpha lactalbumin
4L41 2013-10-02 2.7 Human Lactose synthase: A 2:1 complex between human alpha-lactalbumin and human beta1,4-galactosyltransferase

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
91.7 Alpha-lactalbumin P37154 LALBA_FELCA
94.3 Alpha-lactalbumin P12065 LALBA_PAPCY
100.0 Alpha-lactalbumin P00709 LALBA_HUMAN