Preparation of monoPEGylated human interferon beta-1a: Optimization of the conditions for N-terminal PEGylation

The recombinant human interferon (IFN) beta-1a was modified with polyethylene glycol (PEG). The reaction was performed with the use of activated linear butyraldehyde PEG derivative with a molecular weight of 30 kDa. As a result of the multifactorial experiment, the correlation between the reaction conditions and the yield of the monoPEGylated protein was demonstrated and the optimal PEGylation conditions were established. We developed a one-step chromatographic purification scheme that makes it possible to obtain monoPEG-IFN beta-1a conjugate a purity above 98%. Mass-spectrometric studies showed that the purified conjugate is the PEGylated IFN beta-1a, in which the N-terminal methionine is bound with a PEG molecule. The molecular weight of the conjugate is 54130 Da. The obtained PEG-IFN beta-1a has a specific antiviral activity; it can be considered as a promising candidate in the design of prolonged-release medicine for the treatment of multiple sclerosis.