Polyethylene glycol derivatives, modified peptides and production thereof.

摘要

A polyethylene glycol derivative of the formula <CHEM> wherein R1 and R2 are the same or different and each represents a lower alkyl and m and n are same or different and each represents an optional positive integer which renders the average molecular weight of the polyethylene glycol moiety about 1,000 to 12,000, a peptide modified by said polyethylene glycol derivative and a method for production thereof are described. The polyethylene glycol derivative (I) is capable of modifying the guanidino groups in peptides. The thereby modified peptides are extremely stable, are considerably delayed in biological clearance (i.e. the durability is extended) and exhibit their physiological activities effectively over the long period.