Fmoc-aminooxy-PEG-acid is a type of compound commonly used in pharmaceutical research and development. It is a member of the PEGylation family of compounds, which are polymers of ethylene glycol used to modify the pharmacokinetic properties of drugs. Fmoc-aminooxy-PEG-acid is unique in that it contains both aminooxy and Fmoc functional groups. The aminooxy group is useful for bioconjugation reactions with carboxylic acid groups, while the Fmoc group provides protection for the aminooxy group until it is needed for a reaction. This compound is widely used in drug delivery systems and in the development of bioactive molecules.