A recombinant C121S mutant of bovine beta-lactoglobulin is more susceptible to peptic digestion and to denaturation by reducing agents and heating.Jayat, D., Gaudin, J.C., Chobert, J.M., Burova, T.V., Holt, C., McNae, I., Sawyer, L., Haertle, T.
(2004) Biochemistry 43: 6312-6321
- PubMed: 15147215
- DOI: 10.1021/bi0362469
- Structures With Same Primary Citation
- PubMed Abstract:
- Crystal Structures of the Bovine Beta-Lactoglobulin in the Orthorhombic Space Group C2221: Structural Differences between Genetic Variants a and B and the Nature of Tanford Transition
Oliveira, K.M.G., Valente-Mesquita, V.L., Botelho, M.M., Sawyer, L., Ferreira, S.T., Polikarpov, I.
(2001) Eur J Biochem 268: 477
- Expression of Recombinant Wild Type and Mutant Beta-Lactoglobulin in the Yeast Pichia Pastoris
Wilson, C., Quarrie, L., Allan, G.J., Flint, D.J., Sawyer, L., Holt, C.
(1999) Int J Food Sci Technol 34: 445
The lipocalin beta-lactoglobulin (BLG) is the major whey protein of bovine milk and is homodimeric at physiological conditions. Each monomer contains two disulfide bonds and one cysteine at position 121 (C121). This free thiol plays an important role ...
The lipocalin beta-lactoglobulin (BLG) is the major whey protein of bovine milk and is homodimeric at physiological conditions. Each monomer contains two disulfide bonds and one cysteine at position 121 (C121). This free thiol plays an important role in the heat-induced aggregation of BLG and, possibly, in its conformational stability. We describe here the expression in the yeast Pichia pastoris of a mutant bovine BLG, in which C121 was changed into Ser (C121S). Circular dichroism and high-performance liquid chromatography experiments, together with the X-ray crystal structure, show that the C121S mutant retains a nativelike fold at both neutral and acid pH. The mutation completely blocks the irreversible aggregation induced by heat treatment at 90 degrees C. Compared to the recombinant wild-type protein, the mutant is less stable to temperature and disulfide reducing agents and is much more sensitive to peptic digestion. Moreover, its affinity for 1-anilino-8-naphthalenesulfonate is increased at neutral and acid pH. We suggest that the stability of the protein arising from the hydrophobic effect is reduced by the C121S mutation so that unfolded or partially unfolded states are more favored.
Laboratoire d'Etude des Interactions des Molécules Alimentaires, Institut National de la Recherche Agronomique, rue de la Géraudière, B.P. 71627, 44316 Nantes Cedex 3, France.