β-Lactoglobulin molten globule induced by high pressure

Jian Yang, A. Dunker, Joseph R. Powers, Stephanie Clark, Barry G. Swanson

Research output: Contribution to journalArticle

73 Citations (Scopus)

Abstract

β-Lactoglobulin (β-LG) was treated with high hydrostatic pressure (HHP) at 600 MPa and 50°C for selected times as long as 64 min. The intrinsic tryptophan fluorescence of β-LG indicated that HHP treatment conditions induced a conformational change. HHP treatment conditions also promote a 3-fold increase in the extrinsic fluorescence of 1-anilinonaphthalene-8-sulfonate and a 2.6-fold decrease for cis-paraneric acid, suggesting an increase in accessible aromatic hydrophobicity and a decrease in aliphatic hydrophobicity. Far-ultraviolet circular dichroism (CD) spectra reveal that the secondary structure of β-LG converts from native β-sheets to non-native α-helices following HHP treatment, whereas near-ultraviolet CD spectra reveal that the native tertiary structure of β-LG essentially disappears. Urea titrations reveal that native β-LG unfolds cooperatively, but the pressure-treated molecule unfolds noncooperatively. The noncooperative state is stable for 3 months at 5°C. The nonaccessible free thiol group of cysteine121 in native β-LG became reactive to Ellman's reagent after adequate HHP treatment. Gel electrophoresis with and without β-mercaptoethanol provided evidence that the exposed thiol group was lost concomitant with the formation of S-S-linked β-LG dimers. Overall, these results suggest that HHP treatments induce β-LG into hydrophobic molten globule structures that remain stable for at least 3 months.

Original languageEnglish (US)
Pages (from-to)3236-3243
Number of pages8
JournalJournal of Agricultural and Food Chemistry
Volume49
Issue number7
DOIs
StatePublished - 2001
Externally publishedYes

Fingerprint

lactoglobulins
Lactoglobulins
Hydrostatic Pressure
high pressure treatment
Hydrostatic pressure
Molten materials
Pressure
circular dichroism spectroscopy
NSC 153174
hydrophobicity
thiols
Hydrophobicity
Circular Dichroism
Hydrophobic and Hydrophilic Interactions
Sulfhydryl Compounds
fluorescence
Fluorescence
sulfonates
Dithionitrobenzoic Acid
titration

Keywords

  • β-Lactoglobulin
  • Fluorescence
  • High pressure
  • Hydrophobic probes
  • Molten globule

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Food Science
  • Chemistry (miscellaneous)

Cite this

β-Lactoglobulin molten globule induced by high pressure. / Yang, Jian; Dunker, A.; Powers, Joseph R.; Clark, Stephanie; Swanson, Barry G.

In: Journal of Agricultural and Food Chemistry, Vol. 49, No. 7, 2001, p. 3236-3243.

Research output: Contribution to journalArticle

Yang, Jian ; Dunker, A. ; Powers, Joseph R. ; Clark, Stephanie ; Swanson, Barry G. / β-Lactoglobulin molten globule induced by high pressure. In: Journal of Agricultural and Food Chemistry. 2001 ; Vol. 49, No. 7. pp. 3236-3243.
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