FT-Raman spectroscopy, fluorescent probe, and solvent accessibility study of egg and milk proteins.
Due to possible contribution of both electrostatic and hydrophobic interactions, use of anionic fluorescent probes such as 1-anilinonaphthalene-8-sulfonic acid (ANS) and cis-parinaric acid (CPA) for the measurement of protein surface hydrophobicity (S0) has been controversial. A neutral probe, 6-propionyl-2-(dimethylamino)-naphthalene (PRODAN), may circumvent this problem. To select the best indicator of S0, in this study, the data for nine model proteins in phosphate buffer, pH 7.5, measured using the above-mentioned probes, was compared to their FT-Raman spectra and calculated solvent accessibility values. Log S0 measured using CPA had the highest correlation (r = 0.874) with the intensities of Raman spectral signals at 760 cm(-1) and 2800-3100 cm(-1), which were combined using a mixture design based on the random-centroid optimization. The order of correlation of Raman spectral parameters with S0 values were CPA > PRODAN > ANS. FT-Raman spectroscopy, therefore, identified CPA, followed by PRODAN, as the fluorescent probe of choice for describing surface hydrophobicity. However, the amino acid surface accessibility calculated using the PredictProtein software was not useful in identifying the best fluorescent probe for the measurement of S0.
The University of British Columbia, Faculty of Agricultural Sciences, Food, Nutrition, and Health program, Food Science Building, 6640 N.W. Marine Drive, Vancouver, British Columbia, Canada V6T 1Z4. alizadeh@interchange.ubc.ca
Nooshin
N
Alizadeh-Pasdar
Eunice C Y
EC
Li-Chan
Shuryo
S
Nakai
D015081:2-Naphthylamine / Q000031:analogs & derivatives*; D000818:Animals; D004527:Egg Proteins / Q000737:chemistry*; D005456:Fluorescent Dyes; D008894:Milk Proteins / Q000737:chemistry*; D012997:Solvents; D013059:Spectrum Analysis, Raman
D004527:Egg Proteins; D005456:Fluorescent Dyes; D008894:Milk Proteins; D012997:Solvents; C038517:prodan; D015081:2-Naphthylamine