Heat-Induced Covalent Complex between Casein Micelles and β-Lactoglobulin from Goat's Milk: Identification of an Involved Disulfide Bond
| Autor: | Daniel Mollé, Jacques Fauquant, Saïd Bouhallab, Gwénaële Henry, François Morgan |
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| Rok vydání: | 2001 |
| Předmět: |
Spectrometry
Mass Electrospray Ionization Hot Temperature Stereochemistry Lactoglobulins Covalent Interaction Micelle Casein Animals Molecule Disulfides Beta-lactoglobulin Micelles Chromatography biology Chemistry Goats Intermolecular force Caseins General Chemistry Hydrogen-Ion Concentration Milk Covalent bond biology.protein Female Ultracentrifuge General Agricultural and Biological Sciences Chromatography Liquid |
| Zdroj: | Journal of Agricultural and Food Chemistry. 50:185-191 |
| ISSN: | 1520-5118 0021-8561 |
| Popis: | Goat milk is characterized by a very low heat stability that could be attributed, in part, to the covalent interaction between whey proteins and casein micelles. However, the formation of such a complex in goat milk has never been evidenced. This study was designed to assess whether heat-induced covalent interaction occurs between purified casein micelles and beta-lactoglobulin. We used a multiple approach of ultracentrifugation of heated mixture, chromatographic fractionation of resuspended pellets, sequential enzyme digestion of disulfide-linked oligomers, and identification of disulfide-linked peptides by on-line liquid chromatography-electrospray ionization mass spectrometry (LC-ESI/MS), and tandem MS. We identified three different types of disulfide links: (1) expected intermolecular bridges between beta-Lg molecules; (2) disulfide bond involving two kappa-casein molecules; and (3) a disulfide bond between two peptides, one from beta-Lg and the other from kappa-casein. The involved sites in this last bond were Cys(160) of beta-Lg and Cys(88) of kappa-casein. Although the identified heterolinkage is possibly only one of several different types, the results of this study constitute the first direct evidence of the formation of a covalent complex between casein micelles and beta-lactoglobulin derived from goat milk. |
| Databáze: | OpenAIRE |
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