Comparison of bovine and porcine beta-lactoglobulin: a mass spectrometric analysis.
Nano-electrospray-ionization mass spectrometry (nano-ESI-MS) is applied to comparison of bovine and porcine beta-lactoglobulin (BLG and PLG). The conformational and oligomeric properties of the two proteins under different solvent and experimental conditions are analyzed. The pH-dependence of dimerization is described for the pH range 2-11. The results indicate maximal dimer accumulation at pH 6 for BLG and pH 4 for PLG, as well as a lower stability of the PLG dimer at pH 4 compared to BLG at pH 6. Conformational stability appears to be higher for BLG at acidic pH, but higher for PLG at basic pH. The higher stability of BLG at low pH is revealed by means of either chemical or thermal denaturation. Equilibrium folding intermediates of both proteins are detected. Finally, conditions are found that promote dissociation of the BLG dimer at pH 6 into folded monomers.
Invernizzi
Gaetano
G
Department of Biotechnology and Biosciences, University Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy.
Samalikova
Maria
M
Brocca
Stefania
S
Lotti
Marina
M
Molinari
Henriette
H
Grandori
Rita
R
D000818:Animals; D002417:Cattle; D006863:Hydrogen-Ion Concentration; D007782:Lactoglobulins / Q000737:chemistry* / Q000145:classification / Q000648:ultrastructure*; D011487:Protein Conformation; D012997:Solvents / Q000737:chemistry; D013045:Species Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013552:Swine
D007782:Lactoglobulins; D012997:Solvents