Frank F Davis, Theodorus Van Es, Nicholas C Palczuk: Non-immunogenic polypeptides. Omri M Behr, December 18, 1979: US04179337 (1429 worldwide citation)

Polypeptides such as enzymes and insulin are coupled to polyethylene glycol or polypropropylene glycol having a molecular weight of 500 to 20,000 daltons to provide a physiologically active non-immunogenic water soluble polypeptide composition. The polyethylene glycol or polypropylene glycol protect ...