β-Lactoglobulin molten globule induced by high pressure

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

Research output: Contribution to journalArticle

78 Scopus citations

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

Keywords

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

ASJC Scopus subject areas

  • Chemistry(all)
  • Agricultural and Biological Sciences(all)

Fingerprint Dive into the research topics of 'β-Lactoglobulin molten globule induced by high pressure'. Together they form a unique fingerprint.

  • Cite this