The Binding Ability of α-Lactalbumin and β-Lactoglobulin to Mutagenic Heterocyclic Amines

Abstract

The binding ability of bovine milk proteins with mutagenic heterocyclic amines was investigated. Binding was determined with 2mg of β-lactoglobulin and 20µg of heterocyclic amine in .4ml of pH 7.4, 50mM phosphate buffer, at 37°C, in a shaker for 10min. The unbound heterocyclic amine in protein-free ultrafiltrate was analyzed by HPLC method. The binding of α-lactalbumin, β-lactoglobulin A and β-lactoglobulin B were 90.44, 81.38 and 89.18%, respectively, with 3-amino-l, 4-dimethyl-5H-pyrido[4,3-b]indole; 37.85, 34.04, and 43.90%, respectively, with 3-amino-l-methyl-5H-pyrido[4,3-b]indole; and 49.11, 43.25, and 57.44%. respectively, with 2-amino-6-methyldipyrido[1,2-a:3’,2’-d] imidazole. Binding of β-lactoglobulin and α-lactalbumin to 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole and 3-amino-1-methyl-5H-pyrido [4,3-b]-indole was higher at pH conditions above 7.4, and binding was lost at pH less than 5.5. Maximum binding of both proteins to 2-amino-6-methyl-dipyrido[1,2-a3’,2’-d]imidazole was at pH 7.4, and binding was inhibited at pH conditions above 8.5 and less than 6.5.