Virus-like particles are of interest for several applications, including gene therapy, drug delivery, and as vaccines. Virus-like particles, or VLPs, are made from protein ‘pieces’ called precursor or capsid proteins. The improvement of large-scale production of these precursor proteins is of interest in research. One method being investigated for the VP1 precursor protein, and it is to this that this project applies.
Processes involved in the expression of VP1 result in it being fused to a GST tag – in the complex GST-VP1. Purification of VP1 requires the separation of VP1 from the GST tag, which is achieved by thrombin-catalysed cleavage. This project developed a model for the cleavage of GST-VP1 with thrombin, which formed a basis for further development, and eventually use in scale-up studies of the proposed VP1 production method.
The method involved collection of experimental data and the fitting of this data to rate equations, to obtain reaction rate constants. Matlab was used for this purpose, by non-linear regression using the function nlinfit.
The modelling method used was verified by application to a reaction mechanism in a published article, and replication of the published results. The Michaelis-Menten mechanism was used to simplify the reactions for this first stage of modelling. Further work would involve adjusting the model to include enzyme concentration, which was eliminated in this project due to Michaelis-Menten simplifications.