Formation of Nε-(Carboxymethyl)lysine and loss of lysine in casein glucose-fatty acid model systems

Lima, Maria, Assar, Shima and Ames, Jenny (2010) Formation of Nε-(Carboxymethyl)lysine and loss of lysine in casein glucose-fatty acid model systems. Journal of Agricultural and Food Chemistry, 58 (3). pp. 1954-1958. ISSN 0021-8561

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Abstract

Advanced glycation end-products (AGEs) and advanced lipoxidation end-products (ALEs) form when proteins are heated with reducing sugar or lipid. N?-(Carboxymethyl)lysine (CML) is the most commonly studied AGE/ALE in foods, but the relative importance of dietary sugar and lipid as its precursors is uncertain. The aim of this study was to determine the relative amounts of CML formed from fatty acid and glucose in a model food system. Model systems were prepared by heating casein (3.2%) with glucose or fatty acid (oleic, linoleic, linolenic, or arachidonic acid) (200 mM) or a mixture of glucose and linolenic acid (200 mM of each precursor) at 95 °C for up to 8 h. CML was determined by ultrapressure liquid chromatography?tandem mass spectrometry. The amount of CML formed from casein and glucose incubated at 95 °C for 8 h was 15-fold higher than that obtained when casein was heated with arachidonic acid under the same conditions. However, the loss of lysine in the casein?arachidonic acid incubations was 83% compared to 54% loss in the casein?glucose incubations. The loss of lysine in casein?fatty acid model systems increased with degree of unsaturation of the fatty acid. The formation of lipid peroxidation products during oxidation of fatty acids might be a potent factor for loss of lysine in the casein?fatty acid systems.

Item Type:	Article
Uncontrolled Keywords:	High performance liquid chromatography, Mass spectrometry, Glycosylation
Subjects:	C700 Molecular Biology, Biophysics and Biochemistry F100 Chemistry
Department:	Faculties > Health and Life Sciences > Applied Sciences
Depositing User:	EPrint Services
Date Deposited:	26 Apr 2010 11:15
Last Modified:	12 Oct 2019 18:25
URI:	http://nrl.northumbria.ac.uk/id/eprint/3072

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