Carboxymethyldextran lactone: a preactivated polymer for amine conjugations.

The linking of amino haptens to carboxymethyldextran (CMD) requires carboxyl activation, for example, via carbodiimdes. We have discovered that substantial N-acylurea, derived from these carbodiimides, can be trapped on the CMD backbone. As an alternative, CMD can be conveniently lactonized by heating in inert solvents, and this carboxymethyldextran lactone (CLD) can be employed directly for amine conjugation.