Structural changes of β-casein induced by temperature and ph analysed by nuclear magnetic resonance, fourier-transform infrared spectroscopy, and chemometrics

Tatijana Markoska, Davor Daniloski, Todor Vasiljevic, Thom Huppertz*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

23 Citations (Scopus)

Abstract

This study investigated structural changes in β-casein as a function of temperature (4 and 20C) and pH (5.9 and 7.0). For this purpose, nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR) spectroscopy were used, in conjunction with chemometric analysis. Both temperature and pH had strongly affected the secondary structure of β-casein, with most affected regions involving random coils and α-helical structures. The α-helical structures showed great pH sensitivity by decreasing at 20C and diminishing completely at 4C when pH was increased from 5.9 to 7.0. The decrease in α-helix was likely related to the greater presence of random coils at pH 7.0, which was not observed at pH 5.9 at either temperature. The changes in secondary structure components were linked to decreased hydrophobic interactions at lower temperature and increasing pH. The most prominent change of the α-helix took place when the pH was adjusted to 7.0 and the temperature set at 4C, which confirms the disruption of the hydrogen bonds and weakening of hydrophobic interactions in the system. The findings can assist in establishing the structural behaviour of the β-casein under conditions that apply as important for solubility and production of β-casein.

Original languageEnglish
Article number7650
JournalMolecules
Volume26
Issue number24
DOIs
Publication statusPublished - 17 Dec 2021

Keywords

  • FTIR
  • NMR
  • PH
  • Secondary structure
  • Temperature
  • β-casein

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