Patent ID: 7238842

Claim:
A method for preparing a compound of the formula biotin-Linker-A—X comprising coupling a compound of formula biotin-Y with a compound of formula Z-Linker-A—X, wherein Y and Z are groups that can react to link biotin to Linker-A—X, wherein the linker is a branched or unbranched carbon chain comprising from 2 to 30 carbon atoms, which chain optionally includes one or more double or triple bonds, and which chain is optionally substituted with one or more hydroxy or oxo (═O) groups, wherein one or more of the carbon atoms in the chain is optionally replaced with a non-peroxide —O—, —S— or —NH—, wherein the linker-A separates biotin and X by at least 11 atoms, wherein A—X is a substrate for a dehalogenase, wherein A is (CH 2 ) n and n=2-10, wherein X is a halogen, wherein biotin is a functional group is capable of being coupled through its carboxy terminus to the linker, and wherein biotin-Y is an activated ester of biotin and wherein Z is an amine suitable to react with the activated ester to form an amide bond.