Conformation changes of beta-lactoglobulin: an ATR infrared spectroscopic study of the effect of pH and ethanol.
Fourier transform infrared spectroscopy has been applied to investigate the secondary structural changes of beta-lactoglobulin in water/ethanol mixtures. The studies were carried out at two different pHs and at high protein concentrations. The spectra were recorded using an attenuated total reflection cell. The amide I band of beta-lactoglobulin in water reveals large amounts of intra extended beta-sheet structure. About 20% ethanol, beta-lactoglobulin unfolds and beta-strand formation is observed. alpha-Helices are built up by increasing the ethanol concentration up to 30%. In 50% ethanol, beta-lactoglobulin gels providing the apparent pH are neutral. The secondary structural changes of beta-lactoglobulin were observed on the similarity maps obtained by Principal Component Analysis.
Dufour
E
E
LEIMA, Institut National de la Recherche Agronomique, Nantes, France.
Robert
P
P
Bertrand
D
D
Haertlé
T
T
D000818:Animals; D002417:Cattle; D000431:Ethanol / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007782:Lactoglobulins / Q000737:chemistry*; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared
D007782:Lactoglobulins; D000431:Ethanol