title: [On the occurence of isopeptide bonds in heated milk protein (author's transl)].
abstract: Milk, milk products and individual milk proteins were subjected to different heat treatments either as powders or in aquous systems. After complete hydrolysis of the peptide bonds (alpha-amide bonds) by a system of four proteinases or peptidases, respectively, the samples were analysed for isopeptides. For this purpose, two chromatographic ion exchange systems were developed, each of which separates Nepsilon-(beta-aspartyl-)lysine (Asp Lys) as well as Nepsilon-(gamma-glutamyl-)lysine (Glu Lys) from the common amino acids. In samples, heated 24 h for at least 120 degrees C, 2-5% of the lysine residues are incorporated in Glu Lys-bonds. Under the heating conditions used in dairy practice, no isopeptide bonds were formed.
mesh_terms: D000818:Animals; D002417:Cattle; D003611:Dairy Products / Q000032:analysis; D005260:Female; D005504:Food Analysis / Q000379:methods; D006358:Hot Temperature; D008894:Milk Proteins / Q000032:analysis*; D010455:Peptides / Q000032:analysis*
chemical_list: D008894:Milk Proteins; D010455:Peptides
vernacular_title: Zum Vorkommen von Isopeptidbindungen in erhitztem Milcheiweiss