Chemically modified lymphokine and production thereof

Abstract

The invention provides chemically modified lymphokines comprising a lymphokine moiety and at least one polyethylene glycol moiety of the formula: R.paren open-st.O--CH 2 CH 2 .paren close-st. n wherein R is a protective group for the terminal oxygen and n is at least one, bonded directly to at least one primary amino group of the lymphokine moiety, and a method of producing the same. The chemically modified lymphokines according to the invention can be produced by reacting a lymphokine with an aldehyde of the formula R.paren open-st.O--CH 2 CH 2 .paren close-st. n-1 O--CH 2 CHO wherein R and n are as defined above, in the presence of a reducing agent. The chemically modified lymphokines according to the invention are useful as drugs, among others.

What is claimed is: 
     
       1. A process of making an activated polyethylene glycol methyl ether aldehyde for the modification of proteins, the process comprising the steps of: (a) dissolving a polyethylene glycol methyl ether aldehyde in a 0.2M phosphate buffer at pH 7.0; and   (b) adding sodium cyanoborohydride to the solution obtained in step (a).