PEGylation reagents and compounds formed therewith

This invention relates to active derivatives of polyethylene glycol and related hydrophilic polymers and to methods for their synthesis for use in modifying the characteristics of surfaces and molecules. The invention also relates to polypeptides that have been covalently bonded to such active derivatives and methods for making the same. Compounds are disclosed having the general formula R-X-R, wherein Rand Rare biologically active groups, at least one of which is polypeptidic. X is a non-peptidic polymeric group. Rand Rmay be the same or different. Preferred Rand Rgroups are TNF inhibitors.