title: The least number of phosphate groups for crosslinking of casein by colloidal calcium phosphate.
abstract: Artificial casein micelles were formed with whole human casein at 20 mM calcium, 17 mM phosphate, and 10 mM citrate. The casein micelles disaggregated by 6 M urea were separated by high performance gel chromatography on a TSK-GEL G4000SW column into crosslinked and monomeric fractions. When the crosslinked casein fraction was analyzed by high performance ionexchange chromatography on a TSK-GEL DEAE-5PW column, a small peak, representing the 3-P component of human beta-casein, and distinct peaks of the 4-P and 5-P components were found. Artificial casein micelles were formed from mixtures of each purified component of human beta-casein and bovine kappa-casein, disaggregated by urea, and separated on a TSK-GEL G4000SW column. The casein aggregates crosslinked by colloidal calcium phosphate were formed in artificial casein micelles of the 3-P and 4-P components. In contrast, no crosslinkage was formed in artificial micelles of the 1-P and 2-P components. The results indicate that at least three phosphate groups are needed for crosslinking of casein by colloidal calcium phosphate.
authors.affiliation: Department of Biochemical Science and Technology, Faculty of Agriculture Kagoshima University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Aoki
authors.forename: T
authors.initials: T
authors.lastname: Umeda
authors.forename: Y
authors.initials: Y
authors.lastname: Kako
mesh_terms: D000818:Animals; D002130:Calcium Phosphates / Q000737:chemistry*; D002364:Caseins / Q000737:chemistry*; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D003102:Colloids; D003432:Cross-Linking Reagents / Q000737:chemistry*; D006801:Humans; D008823:Micelles; D008895:Milk, Human / Q000737:chemistry*
chemical_list: D002130:Calcium Phosphates; D002364:Caseins; D003102:Colloids; D003432:Cross-Linking Reagents; D008823:Micelles; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous