Interaction of Human alpha-Lactalbumin with Fatty Acids: Determination of Binding Parameters

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C. Barbana^*, M. D. Pérez, C. Pocovi, L. Sánchez, and Z. Wehbi

Tecnología y Bioquímica de los Alimentos, Facultad de Veterinaria, Universidad de Zaragoza, Miguel Servet, 177, 50013-Zaragoza, Spain; fax: (34-976) 761-590; E-mail: barbana@unizar.es

^* To whom correspondence should be addressed.

Received September 27, 2007; Revision received October 17, 2007

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The interaction of holo- and apo-forms of human alpha-lactalbumin with fatty acids was studied by a partition equilibrium method. Apo-alpha-lactalbumin, obtained by treatment with EDTA, displays one binding site for fatty acids, the association constants for oleic and palmitic acids being 1.9·10⁶ and 4.2·10⁵ M^-1, respectively. However, holo-alpha-lactalbumin was unable to bind fatty acids as measured by this technique. Likewise, no fatty acids bound to holo-alpha-lactalbumin, isolated using nondenaturing conditions, were detected by gas chromatography. These results demonstrate that the conformational change induced in alpha-lactalbumin by the removal of calcium enables the protein to interact with fatty acids.

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KEY WORDS: human alpha-lactalbumin, fatty acids, binding, partition equilibrium

DOI: 10.1134/S0006297908060126

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