title: Determination of heat-induced changes in the protein secondary structure of reconstituted livetins (water-soluble proteins from hen's egg yolk) by FTIR.
abstract: This study characterized the impact of technological treatments on the protein secondary structure of a newly developed egg yolk livetin formulation and its components α-livetin, which is identical with chicken serum albumin, and γ-livetin, the bioactive antibody immunoglobulin Y. Fourier transform infrared (FTIR) spectroscopy at 25 °C revealed that the largest proportion of conformal elements comprised intramolecular (native) β-sheets (60-80%) in γ-livetin, and α-helices/random coils (60.59%) in α-livetin. In reconstituted freeze-dried livetins, the main protein conformations were also intramolecular (native) β-sheets (55.08%) and α-helices/random coils (30.51%), but upon heating from 25 to 95 °C, the former decreased sigmoidally at the onset-of-denaturation temperature (TOD (FTIR)) of 69.5 °C, concomitant with a sigmoidal increase in intermolecular (denatured) β-sheets at a TOD (FTIR) of 72.4 °C and a sigmoidal decrease in IgY activity at TOD (ELISA) of 67.5 °C. Reconstituted spray-dried livetins showed less native β-sheets and significantly lower TOD (FTIR) values than freeze-dried livetins.
authors.affiliation: Center for Food Sciences, Institute of Food Toxicology and Analytical Chemistry, Department of Analytical Chemistry, University of Veterinary Medicine Hannover Foundation, Bischofsholer Damm 15, D-30173 Hannover, Germany.
authors.forename: Timo
authors.initials: T
authors.lastname: Ulrichs
authors.affiliation: Center for Food Sciences, Institute of Food Toxicology and Analytical Chemistry, Department of Analytical Chemistry, University of Veterinary Medicine Hannover Foundation, Bischofsholer Damm 15, D-30173 Hannover, Germany. Electronic address: astrid.drotleff@tiho-hannover.de.
authors.forename: Astrid M
authors.initials: AM
authors.lastname: Drotleff
authors.affiliation: Center for Food Sciences, Institute of Food Toxicology and Analytical Chemistry, Department of Analytical Chemistry, University of Veterinary Medicine Hannover Foundation, Bischofsholer Damm 15, D-30173 Hannover, Germany.
authors.forename: Waldemar
authors.initials: W
authors.lastname: Ternes
mesh_terms: D000818:Animals; D002645:Chickens; D004527:Egg Proteins / Q000737:chemistry*; D004530:Egg Yolk / Q000737:chemistry*; D005612:Freeze Drying; D006358:Hot Temperature; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*
chemical_list: D004527:Egg Proteins; C039690:livetin
keywords: Fourier transform infrared spectroscopy (FTIR); Freeze-drying; Heating; Immunoglobulins from yolk (IgY); Livetins fraction; Protein secondary structure