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Mechanism of interaction of Pb(II) with milk proteins: a case study of alpha-casein.

Srinivas, S. and Kaul, Purnima and Prakash, V. (2007) Mechanism of interaction of Pb(II) with milk proteins: a case study of alpha-casein. Journal of agricultural and food chemistry, 55 (22). pp. 9283-8. ISSN 0021-8561

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Alpha-casein is the major casein protein fraction from bovine milk and is responsible for binding to many ligands. This paper reports the results on the interaction of Pb(II) with alpha-casein. The interaction studies by spectroscopic titration indicate that Pb(II) has two binding sites with an association constant (ka) of (2.3 +/- 0.2) x 10 (5) M(-1). Raman spectra of the alpha-casein-Pb(II) complex show reduction in the amide I region as well as minor perturbations in the sulfhydryl region of alpha-casein. Stopped-flow studies show that the reaction mechanism of Pb(II) follows a pseudo-first-order reaction with a rate of 25 +/- 6 s(-1). The stopped-flow time-resolved spectra show peaks at 330 and 360 nm, correlating to Pb(II)-thiolate bands in the UV absorption spectra. Modification of cysteines present in alpha-casein does not result in binding of lead, indicating that cysteines could be one of the Pb(II) binding sites.

Item Type: Article
Uncontrolled Keywords: Lead; r-casein; stopped flow; hydrophobicity; cysteines; Raman spectra; milk; circular dichroism
Subjects: 500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 29 Protein Chemistry
600 Technology > 08 Food technology > 27 Dairy products
Divisions: Protein Chemistry and Technology
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 07 Aug 2008 11:36
Last Modified: 01 Jul 2015 12:55
URI: http://ir.cftri.com/id/eprint/1834

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