Towards an improved predictor for the colloidal stability of unfolded proteins through probing aggregation behaviour in solutions containing chemical denaturants

  • Ibrahim Alsabih

Student thesis: Phd


Protein-based therapeutics are widely used for the treatment of different diseases such as anti-cancer and anti-diabetes drugs. Throughout the manufacturing and formulation process of protein drugs, the protein stability must be sustained for long-term storage and the formulation must be used for efficacious delivery that avoids adverse immunogenic side effects. The main physical degradation process is by protein aggregation, which can be defined as a multi-stage process in which mis-folded proteins irreversibly associate with each other forming a soluble or insoluble aggregate. A key stumbling block to predicting aggregation is that key intermediates in the pathways are partially folded proteins, which occur very transiently and at low concentrations during typical formulation conditions. Traditional approaches to overcome this problem use increased temperature to increase the populations of the aggregate precursors thereby accelerating the aggregation process so that it can be studied on reasonable timescales. A common prediction depends on the Arrhenius relationship between protein degradation and temperature. Unfortunately, this approach is not often successful because many proteins do not follow Arrhenius kinetics due to exhibiting multiple aggregation pathways with different temperature dependencies (Wang and Roberts, 2013). This thesis is directed at understanding the aggregation behaviour of protein solutions under chemically denaturing conditions towards developing an alternative predictive approach for assessing storage stability. As such, ovalbumin solutions were studied over a range of denaturant concentrations in the absence of excipients and in the presence of series of excipients (ArgHCl, ArgGlu, NaCl, Na2SO4, NaSCN, ATP, STPP, trehalose and sucrose), using static and dynamic light scattering to identify and better understand the aggregation and find an alternative for estimating the colloidal stability, which is an important indicator for protein aggregation.
Date of Award31 Dec 2022
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorRobin Curtis (Supervisor) & Alain Pluen (Supervisor)

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