Studies on the properties of aggregating casein systems

Paterson, Elspeth (1980) Studies on the properties of aggregating casein systems. PhD thesis, University of Glasgow.

Abstract

The growth in weight average molecular weight in aggregating casein systems was observed using light scattering. The kinetics of the aggregation of both α[sl]-casein and β-casein in the presence of Ca[2+] were determined by linking a stopped flow apparatus to the light detection system. The effect of temperature on both of these reactions was also investigated. Two stages were identified in the reaction. Precipitate fractions of casein were determined for the combinations of Ca[2+] and casein used in kinetic experiments under the same conditions. On the basis of results from these experiments a mechanism for the Ca[2+] induced aggregation of αs1-casein was proposed. The first stage of the reaction was described as a series of multimerization equilibria which are dependent upon the average charge on the αs1-casein molecule. This equilibrium produces an octamer which is sufficiently large to precipitate from solution upon further aggregation. The rate constant for this second stage association of the reaction has been found to be dependent on the charge and also the concentration of precipitable material. The equilibrium stage of the aggregation reaction is more temperature dependent than the precipitation process. Although many similarities were observed between the β-casein and the αs1-casein aggregation, there were differences, mainly ascribable to self-aggregation of β-casein in the absence of Ca[2+]. The effect of temperature on the reaction kinetics of β-casein was also investigated and in common with αs1-casein aggregation the first stage is more temperature dependent than the second. Higher fractions of β-casein are precipitable than for the same Ca[2+] and αs1-casein concentration at their respective reaction temperatures. The nature of the precipitable aggregate of β-casein was not defined.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: From title page: Hannah Research Institute, Ayr.
• Subjects: Q Science > QD Chemistry
• Colleges/Schools: College of Science and Engineering
• Supervisor's Name: Dalgleish, Dr. D.G.
• Date of Award: 1980
• Depositing User: Enlighten Team
• Unique ID: glathesis:1980-83066
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 02 Aug 2022 14:51
• Last Modified: 02 Aug 2022 14:51
• Thesis DOI: 10.5525/gla.thesis.83066
• URI: https://theses.gla.ac.uk/id/eprint/83066