Biotinylation Reagents Containing Discrete PEG Linkers

Biotin modification reagents are widely used to attach a biotin group to proteins or other molecules for subsequent use in avidin, streptavidin, or NeutrAvidin separations or assays. Traditional biotin compounds containing aliphatic or other hydrophobic linker arms are discussed in detail in Chapter 11. In this section, the biotin-PEG compounds exclusively are discussed due to their unique hydrophilic properties, which include low nonspecific binding character and low immunogenicity. 

The use of discrete PEG spacers in the construction of biotinylation compounds not only increases the water solubility of the modification reagent itself, but significantly increases the hydrophilicity and stability of proteins modified with them. Even when high modification levels 

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