Structural and conformational changes of β-lactoglobulin B : an infrared spectroscopic study of the effect of pH and temperature

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DOIResolve DOI: http://doi.org/10.1016/0167-4838(88)90152-5
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TypeArticle
Journal titleBiochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology
ISSN01674838
Volume957
Issue1
Pages1120
Subjectβ-Lactoglobulin B; Protein conformation; Protein denaturation; Infrared spectroscopy
AbstractInfrared spectra of 2.5 mM solutions of β-lactoglobulin B were recorded as a function of pH (from pH 2 to pH 13) and as a function of temperature (from −100°C to +90°C). An analysis of the pH- and temperature-induced changes in the secondary structures was performed based on changes in the conformation-sensitive amide I bands of β-lactoglobulin. Whereas the total of β-structure remains constant (56–59%) between pH22 and pH 10, the proportions of the various β-components do change. In particular, the dimerization of the monomeric protein, induced by raising the pH from 20 to 3, leads to an increase in the intensity of the 1636 cm−1 band (associated with antiparallel β-sheet), at the expense of the 1626 cm−1 band (associated with exposed β-strands). Both the thermal and alkaline denaturation of β-lactoglobulin occur in two distinct stages. Although the spectra (i.e., the structures) after complete thermal or alkaline denaturation are clearly different, the spectrum of the protein after the first stage of thermal denaturation (at about 60°C) is the same as that after the first stage of alkaline denaturation (at pH 11), suggesting a common denaturation intermediate, which probably represents a crossover point in a complex potential hypersurface.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada
Peer reviewedYes
NPARC number23001187
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Record identifier3f8c97aa-348b-483d-9973-fdeeccc52e50
Record created2017-01-03
Record modified2017-01-03
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