Aminooxy-PEG4-acid is a PEG linker containing an aminooxy group and a terminal carboxylic acid. The hydrophilic PEG spacer increases solubility in aqueous media. The aminooxy group can be used in bioconjugation. It reacts with an aldehyde to form an oxime bond. If a reductant is used, it will form a hydroxylamine linkage. The terminal carboxylic acid can react with primary amine groups in the presence of activators (e.g. EDC, or HATU) to form a stable amide bond. Aminooxy compounds are very reactive and sensitive; they cannot be stored for long term. Immediate use (within 1 week) is highly recommended. Aminooxy-PEG4-acid is not stable as a neat compound; it is sold as 1.0M aqueous solution.
