Effects of amino acid substitutions in the hydrophobic core of alpha-lactalbumin on the stability of the molten globule state.


Abstract

Five mutant alpha-lactalbumins, with one or two amino acid substitution(s) in the B helix, were engineered to examine the relation between the stability of the molten globule state and the hydrophobicity of these amino acids. The mutation sites (Thr29, Ala30 and Thr33) have been chosen on the basis of comparison of the amino acid sequences of goat, bovine and gunea pig alpha-lactalbumin, in which the guinea pig protein shows a remarkably more stable molten globule than the other proteins. The recombinant proteins were expressed Escherichia coli and then purified and refolded efficiently to produce the active proteins. The stability of the molten globule state of these engineered proteins has been investigated by urea-induced unfolding transition under an acidic condition (pH 2.0), where the molten globule state is stable in the absence of urea. The results show that the molten globule state is stabilized by the amino acid substitutions which raise the hydrophobicity of the residues, suggesting that the hydrophobic core in a globular protein plays an important role in the stability of the molten globule state. The change in stabilization free energy of the molten globule state caused by each amino acid substitution has been evaluated, and molecular mechanisms of stabilization of the molten globule state are discussed. Study holds ProTherm entries: 2506, 2507, 2508, 2509, 2510, 2511 Extra Details: dG and ddG were measured in the presence of 2.1M urea alpha-lactalbumin; amino acid substitutions; hydrophobic core;,molten globule; refolding

Submission Details

ID: FWrPMNhv

Submitter: Connie Wang

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

Version: 1

Publication Details
Uchiyama H;Perez-Prat EM;Watanabe K;Kumagai I;Kuwajima K,Protein Eng. (1995) Effects of amino acid substitutions in the hydrophobic core of alpha-lactalbumin on the stability of the molten globule state. PMID:8819981
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
3B0K 2012-06-13 1.6 Crystal structure of alpha-lactalbumin
1FKQ 2001-02-14 1.8 RECOMBINANT GOAT ALPHA-LACTALBUMIN T29V
6IP9 2019-02-20 1.85 Crystal Structure of Lanthanum ion (La3+) bound bovine alpha-lactalbumin
1FKV 2001-02-14 2.0 RECOMBINANT GOAT ALPHA-LACTALBUMIN T29I
1HMK 1999-11-26 2.0 RECOMBINANT GOAT ALPHA-LACTALBUMIN
1F6R 2000-12-13 2.2 CRYSTAL STRUCTURE OF APO-BOVINE ALPHA-LACTALBUMIN
1F6S 2000-12-13 2.2 CRYSTAL STRUCTURE OF BOVINE ALPHA-LACTALBUMIN
1HFZ 1997-07-29 2.3 ALPHA-LACTALBUMIN
2G4N 2007-02-20 2.3 Anomalous substructure of alpha-lactalbumin
1HFY 1997-07-07 2.3 ALPHA-LACTALBUMIN

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
94.4 Alpha-lactalbumin Q9TSR4 LALBA_BOSMU
95.1 Alpha-lactalbumin P00711 LALBA_BOVIN
96.5 Alpha-lactalbumin Q9TSN6 LALBA_BUBBU
97.9 Alpha-lactalbumin P09462 LALBA_SHEEP
100.0 Alpha-lactalbumin P00712 LALBA_CAPHI