Mechanisms of protein precipitation for two tannins, pentagalloyl glucose and epicatechin16 (4→8) catechin (procyanidin)

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Titre du document / Document title

Mechanisms of protein precipitation for two tannins, pentagalloyl glucose and epicatechin₁₆ (4→8) catechin (procyanidin)

Auteur(s) / Author(s)

HAGERMAN A. E.⁽¹⁾ ; RICE M. E.⁽¹⁾ ; RITCHARD N. T.⁽¹⁾ ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

⁽¹⁾Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, ETATS-UNIS

Résumé / Abstract

The precipitates that form when purified pentagalloylglucose or a purified procyanidin [epicatechin₁₆ (4→8) catechin; EC₁₆-C] are mixed with bovine serum albumin were quantitatively analyzed. EC₁₆-C is a more efficient protein precipitating agent than pentagalloylglucose on a molar or a mass basis. EC₁₆-C precipitates protein independently of temperature and presence of organic solvent. Precipitation by pentagalloylglucose increases as temperature is increased and decreases when alcohols are present. When tannin is in excess, up to 40 mol of pentagalloylglucose is bound per mole of protein precipitated, but only 20 mol of EC₁₆-C is bound per mole of protein precipitated. The data support different models of precipitation for the two types of tannin: pentagalloylglucose, which is very nonpolar, precipitates by forming a hydrophobic coat around the protein, whereas the much more polar EC₁₆-C forms hydrogen-bonded cross-links between protein molecules.

Revue / Journal Title

Journal of agricultural and food chemistry ISSN 0021-8561 CODEN JAFCAU

Source / Source

1998, vol. 46, n^o7, pp. 2590-2595 (1 p.1/4)

Langue / Language

Anglais

Editeur / Publisher

American Chemical Society, Washington, DC, ETATS-UNIS (1953) (Revue)

Localisation / Location

INIST-CNRS, Cote INIST : 7332, 35400007279988.0270

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