Interaction Between к-Casein and β-Lactoglobulin: Possible Mechanism

Zahurul Haque; Magnus M. Kristjansson; John E. Kinsella

doi:10.1021/jf00077a003

Interaction Between к-Casein and β-Lactoglobulin: Possible Mechanism

Zahurul Haque, Magnus M. Kristjansson, John E. Kinsella^*

^*Corresponding author for this work

Faculty of Physical Sciences

Research output: Contribution to journal › Article › peer-review

63 Citations (Scopus)

Abstract

к-Casein (к-C) and β-lactoglobulin (β-Lg) interact to form a к-C/β-Lg complex (A₄) apparently composed of three molecules of β-Lg and one molecule of к-C. In a freshly dispersed equimolar mixture of native к-C and β-Lg maintained at 25 °C in 20 mM imidazole at pH 6.8, approximately 14% occurred as a к-C/β-Lg A₄complex which increased to about 40% when 20 mM ethylene glycol bis(2-aminoethoxy)-N,N,NʹNʹ-tetraacetic acid (EGTA) was added. The EGTA apparently caused a structural change that resulted in a β-Lg complex (A₃) that was highly reactive with monomeric к-C. This reactivity was quenched in the presence of 2.3 M urea. With time, this A₄complex became stabilized by covalent bonds. Heating at 70 °C increased the rate of formation of the covalently bonded к-C/β-Lg complex. A possible mechanism for the interaction of к-C with β-Lg involves the formation of a β-Lg homotrimer (A₃) complex via hydrophobic interactions that interacts with a к-C molecule.

Original language	English
Pages (from-to)	644-649
Number of pages	6
Journal	Journal of Agricultural and Food Chemistry
Volume	35
Issue number	5
DOIs	https://doi.org/10.1021/jf00077a003
Publication status	Published - 1 Sept 1987

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title = "Interaction Between к-Casein and β-Lactoglobulin: Possible Mechanism",

abstract = "к-Casein (к-C) and β-lactoglobulin (β-Lg) interact to form a к-C/β-Lg complex (A4) apparently composed of three molecules of β-Lg and one molecule of к-C. In a freshly dispersed equimolar mixture of native к-C and β-Lg maintained at 25 °C in 20 mM imidazole at pH 6.8, approximately 14% occurred as a к-C/β-Lg A4complex which increased to about 40% when 20 mM ethylene glycol bis(2-aminoethoxy)-N,N,NʹNʹ-tetraacetic acid (EGTA) was added. The EGTA apparently caused a structural change that resulted in a β-Lg complex (A3) that was highly reactive with monomeric к-C. This reactivity was quenched in the presence of 2.3 M urea. With time, this A4complex became stabilized by covalent bonds. Heating at 70 °C increased the rate of formation of the covalently bonded к-C/β-Lg complex. A possible mechanism for the interaction of к-C with β-Lg involves the formation of a β-Lg homotrimer (A3) complex via hydrophobic interactions that interacts with a к-C molecule.",

author = "Zahurul Haque and Kristjansson, {Magnus M.} and Kinsella, {John E.}",

year = "1987",

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doi = "10.1021/jf00077a003",

language = "English",

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journal = "Journal of Agricultural and Food Chemistry",

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T1 - Interaction Between к-Casein and β-Lactoglobulin

T2 - Possible Mechanism

AU - Haque, Zahurul

AU - Kristjansson, Magnus M.

AU - Kinsella, John E.

PY - 1987/9/1

Y1 - 1987/9/1

N2 - к-Casein (к-C) and β-lactoglobulin (β-Lg) interact to form a к-C/β-Lg complex (A4) apparently composed of three molecules of β-Lg and one molecule of к-C. In a freshly dispersed equimolar mixture of native к-C and β-Lg maintained at 25 °C in 20 mM imidazole at pH 6.8, approximately 14% occurred as a к-C/β-Lg A4complex which increased to about 40% when 20 mM ethylene glycol bis(2-aminoethoxy)-N,N,NʹNʹ-tetraacetic acid (EGTA) was added. The EGTA apparently caused a structural change that resulted in a β-Lg complex (A3) that was highly reactive with monomeric к-C. This reactivity was quenched in the presence of 2.3 M urea. With time, this A4complex became stabilized by covalent bonds. Heating at 70 °C increased the rate of formation of the covalently bonded к-C/β-Lg complex. A possible mechanism for the interaction of к-C with β-Lg involves the formation of a β-Lg homotrimer (A3) complex via hydrophobic interactions that interacts with a к-C molecule.

AB - к-Casein (к-C) and β-lactoglobulin (β-Lg) interact to form a к-C/β-Lg complex (A4) apparently composed of three molecules of β-Lg and one molecule of к-C. In a freshly dispersed equimolar mixture of native к-C and β-Lg maintained at 25 °C in 20 mM imidazole at pH 6.8, approximately 14% occurred as a к-C/β-Lg A4complex which increased to about 40% when 20 mM ethylene glycol bis(2-aminoethoxy)-N,N,NʹNʹ-tetraacetic acid (EGTA) was added. The EGTA apparently caused a structural change that resulted in a β-Lg complex (A3) that was highly reactive with monomeric к-C. This reactivity was quenched in the presence of 2.3 M urea. With time, this A4complex became stabilized by covalent bonds. Heating at 70 °C increased the rate of formation of the covalently bonded к-C/β-Lg complex. A possible mechanism for the interaction of к-C with β-Lg involves the formation of a β-Lg homotrimer (A3) complex via hydrophobic interactions that interacts with a к-C molecule.

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DO - 10.1021/jf00077a003

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JF - Journal of Agricultural and Food Chemistry

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Interaction Between к-Casein and β-Lactoglobulin: Possible Mechanism

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