title: Structural and thermal stability of β-lactoglobulin as a result of interacting with sugar beet pectin.
abstract: Changes in the structural and thermal stability of β-lactoglobulin (β-LG) induced by interacting with sugar beet pectin (SBP) have been studied by circular dichroism (CD), Fourier transform infrared, and steady-state as well as time-resolved fluorescence spectroscopic techniques. It has been demonstrated that SBP not only is capable of binding to native β-LG but also causes a significant loss in antiparallel β-sheet, ∼10%, accompanied by an increase in either random coil or turn structures. In addition, the interaction also disrupted the environments of all aromatic residues including Trp, Phe, and Tyr of β-LG as evidenced by near-UV CD and fluorescence. When preheated β-LG was combined with SBP, the secondary structure of β-LG was partially recovered, ∼4% gain in antiparallel β-sheet, and Trp19 fluorescence was recovered slightly. Although forming complexes with SBP did not significantly impact the thermal stability of individual secondary structural elements of β-LG, the environment of Trp19 was protected considerably.
authors.affiliation: Dairy and Functional Foods Research Unit and ‡Biobased and Other Animal Co-products Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture , Wyndmoor, Pennsylvania 19038, United States.
authors.forename: Phoebe X
authors.initials: PX
authors.lastname: Qi
authors.forename: Edward D
authors.initials: ED
authors.lastname: Wickham
authors.forename: Rafael A
authors.initials: RA
authors.lastname: Garcia
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D027461:Beta vulgaris / Q000737:chemistry*; D002942:Circular Dichroism; D004044:Dietary Proteins / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007782:Lactoglobulins / Q000737:chemistry*; D015394:Molecular Structure; D010368:Pectins / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000596:Amino Acids; D004044:Dietary Proteins; D007782:Lactoglobulins; D010368:Pectins