1 - Functional Targets

Abstract

Modification and conjugation techniques are dependent on two interrelated chemical reactions: the reactive functional groups present on the various cross-linking or derivatizing reagents and the functional groups present on the target macromolecules to be modified. Without both these types of functional groups being available and chemically compatible, the process of derivatization would be unfeasible. The reactive functional groups on cross-linking reagents, tags, and probes provide the means to label specifically certain target groups on ligands, peptides, proteins, carbohydrates, lipids, synthetic polymers, nucleic acids, and oligonucleotides. Knowledge of the main mechanisms by which the reactive groups couple with target functional groups provides the ways to design a modification or conjugation strategy. The basis for successful chemical modification is choosing the correct reagent systems that can react with the chemical groups available on target molecules. The principal reactive functional groups commonly encountered on bioconjugate reagents are now present on scores of commercially obtainable compounds. This chapter describes the major targets for these reagent systems. The functional groups discussed are found on virtually every conceivable biological molecule, including amino acids, peptides, proteins, sugars, carbohydrates, polysaccharides, nucleic acids, oligonucleotides, lipids, and complex organic compounds.