Chemo-Enzymatic PEGylation/POxylation of Murine Interleukin‑4

Interleukin-4 (IL-4)
is a potentially interesting anti-inflammatory
therapeutic, which is rapidly excreted. Therefore, serum half-life
extension by polymer conjugation is desirable, which may be done by
PEGylation. Here, we use PEtOx as an alternative to PEG for bioconjugate
engineering. We genetically extended murine IL-4 (mIL-4) with the d-domain of insulin-like growth factor I (IGF-I), a previously
identified substrate of transglutaminase (TG) Factor XIIIa (FXIIIa).
Thereby, engineered mIL-4 (mIL-4-TG) became an educt for TG catalyzed
C-terminal, site-directed conjugation. This was deployed to enzymatically
couple an azide group containing peptide sequence to mIL-4, allowing
C-terminal bioconjugation of polyethylene glycol or poly­(2-ethyl-2-oxazoline).
Both bioconjugates had wild-type potency and alternatively polarized
macrophages.