Contribution of the 6-120 disulfide bond of alpha-lactalbumin to the stabilities of its native and molten globule states.


The unfolding and refolding of a derivative of alpha-lactalbumin, in which the disulfide bond between Cys6 and Cys120 is selectively reduced and S-carboxymethylated, are investigated by equilibrium and kinetic circular dichroism measurements. The native conformation of this derivative is known to be essentially identical to that of intact alpha-lactalbumin. The equilibrium unfolding of the derivative involves a stable intermediate, which is also similar to the molten globule state of the disulfide intact protein. The results of stopped-flow circular dichroism experiments show that the same intermediate is formed rapidly as a transient intermediate in kinetic refolding. The conformational stabilities for the native and intermediate states have been estimated and compared with the stabilities for the corresponding states of intact alpha-lactalbumin. The stabilization of the native state by the disulfide has been interpreted in terms of a decrease in chain entropy in the unfolded state and elimination of the strain imposed on the disulfide bond in the native state. The molten globule state is also stabilized by the disulfide bond, although the degree of stabilization of the molten globule state is smaller than of the native state. The results suggest that, in the molten globule state, some ordered structures are present within the loop moiety formed by the 6-120 disulfide. Study holds ProTherm entries: 4789 Extra Details: disulfide bond; molten globule state; chain entropy;,loop moiety

Submission Details

ID: qKu9o6Ta

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:27 p.m.

Version: 1

Publication Details
Ikeguchi M;Sugai S;Fujino M;Sugawara T;Kuwajima K,Biochemistry (1992) Contribution of the 6-120 disulfide bond of alpha-lactalbumin to the stabilities of its native and molten globule states. PMID:1472507
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 UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Alpha-lactalbumin P00711 LALBA_BOVIN
99.3 Alpha-lactalbumin Q9TSR4 LALBA_BOSMU
98.6 Alpha-lactalbumin Q9TSN6 LALBA_BUBBU
97.2 Alpha-lactalbumin P09462 LALBA_SHEEP
95.1 Alpha-lactalbumin P00712 LALBA_CAPHI