Reagents Targeted to Specic Functional Groups
Since cross-linking reagents are chemical modifying agents, their efŠciencies in linking two moieties depend on their speciŠcity toward the particular functional groups in the components to be linked. For proteins, these are the reactive groups of amino acid side chains; for nucleic acids, the heterocyclic base nitrogen, the amino groups, and the carbonyl oxygen. In order to link two species together, the choice of reagent is critical to the success of the cross-linking and conjugation. In cases wherein a speciŠc group is known to react, a logical choice of cross-linker may be made. Such a choice requires an understanding of the speciŠcity of the reagents. In this connection, this chapter will review the basic factors of protein modiŠcation and agents speciŠc for functional groups.