Susceptibility of protein therapeutics to spontaneous chemical modifications by oxidation, cyclization, and elimination reactions

Abstract

Peptides and proteins are preponderantly emerging in the drug market, as shown by the increasing number of biopharmaceutics already approved or under development. Biomolecules like recombinant monoclonal antibodies have high therapeutic efficacy and offer a valuable alternative to small-molecule drugs. However, due to their complex three-dimensional structure and the presence of many functional groups, the occurrence of spontaneous conformational and chemical changes is much higher for peptides and proteins than for small molecules. The characterization of biotherapeutics with modern and sophisticated analytical methods has revealed the presence of contaminants that mainly arise from oxidation-and elimination-prone amino-acid side chains. This review focuses on protein chemical modifications that may take place during storage due to (1) oxidation (methionine, cysteine, histidine, tyrosine, tryptophan, and phenylalanine), (2) intra-and inter-residue cyclization (aspartic and glutamic acid, asparagine, glutamine, N-terminal dipeptidyl motifs), and (3) β-elimination (serine, threonine, cysteine, cystine) reactions. It also includes some examples of the impact of such modifications on protein structure and function.

Thiyl Radical Reactions in the Chemical Degradation of Pharmaceutical Proteins

“…The physical and chemical stability of proteins are critical for the efficacy and safety of protein therapeutics [1,2]. The reactions of free radicals play an important role in the chemical degradation of peptide and protein therapeutics in pharmaceutical formulations.…”

Influence of spatial structure on protein damage susceptibility – A bioinformatics approach

“…They also mention the problem in connection with storage of biotherapeutics for longer durations. It is notable that some other AAs mentioned in [16] like histidine, methionine and phenylalanine were just ranked average in our score.…”

“…This is desirable, for example, in order to subsequently industrially modify proteins [37]. An important benefit for synthetic biology is the knowledge about the susceptibility of proteins to oxidation in connection with storage and the associated degradation [16]. It is also known that proteins with susceptible AAs (tyrosine) on the surface are relevant for biological aging and age-related disease [38].…”

“…There, the authors score the structures of proteins for their susceptibility to aggregate and call it AggScore [15]. An additional study (review) addressed AAs in the context of oxidation, which also ranked highest in our score (cysteine, tyrosine and tryptophan) [16]. They also mention the problem in connection with storage of biotherapeutics for longer durations.…”

Influence of spatial structure on protein damage susceptibility: a bioinformatics approach

“…There, the authors score the structures of proteins for their susceptibility to aggregate and call it AggScore 21 . An additional study (review) addressed AAs in the context of oxidation, which also ranked highest in our score (cysteine, tyrosine, and tryptophan) 22 . They also mention the problem in connection with the storage of biotherapeutics for longer durations.…”