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INTERACTION OF ZN(II) WITH BOVINE MILK α‐CASEIN: STRUCTURE–FUNCTION STUDY
Author(s) -
SRINIVAS S.,
PRAKASH V.
Publication year - 2011
Publication title -
journal of food biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 47
eISSN - 1745-4514
pISSN - 0145-8884
DOI - 10.1111/j.1745-4514.2010.00453.x
Subject(s) - zinc , chemistry , micronutrient , casein , whey protein , food science , fortification , organic chemistry
ABSTRACT α‐Casein is the major casein from bovine milk, responsible for binding to metal ions. Interaction of α‐casein with Zn(II) studied by equilibrium dialysis indicates the presence of 17.0 ± 2.0 binding sites for Zn(II) with two association constants ka10.2 ± 0.03 × 10 6 M –1 and k a2 2.7 ± 0.3 × 10 6 M –1 , respectively. Far‐Ultraviolet Circular dichroic measurement shows formation of secondary structures in the presence of Zn(II). Fluorescence quenching studies by acrylamide shows blue shift in the emission maxima and decreased Stern–Volmer constant from 10.4 to 4.1 M ‐ 1 . The kinetics of binding as analyzed by stopped flow shows pseudo‐first‐order rate of 37 ± 5 s ‐ 1 . Holistically, this interaction leads to formation of stable complexes, useful for fortification of milk‐based products with micronutrient zinc.PRACTICAL APPLICATIONS Zinc is an essential micronutrient and zinc deficiency leads to many diseases encompassing neonatal growth, immunity, hair loss, diarrhea, hypogonadism in males and eye and skin lesions which are reported. Understanding the zinc‐binding mechanism to the major milk protein α‐casein and, subsequently, structural changes of the α‐casein will help to prepare better zinc‐based products. Such fortification could help to meet the increase in physiological availability of zinc for the needy and could make a difference.