Long chain carboxylic acid imide ester

摘要

Provided is a long chain carboxylic acid imide ester (I) represented by the following general formula (I) <IMAGE> (I) wherein W is a divalent long chain hydrocarbon group which may optionally be interrupted by one or more groups each independently selected from the group consisting of an oxygen atom, a sulfur atom and a group of -N(R1)- (R1 being a lower alkyl group) and X represents a divalent hydrocarbon group which may optionally be substituted, or salts thereof. The above long chain carboxylic acid imide ester or its salts is useful for modifying enzymes or proteins having biological activities to give their derivatives which have, while retaining most of the original biological activities, an extremely prolonged plasma half-life as compared with the proteins and have no antigenecities and can be administered to animals.