Aminooxy-PEG2-methane is a small molecule PEG linker containing an aminooxy group and a methane group. 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. Aminooxy compounds are very reactive and sensitive; they cannot be stored for long term. Immediate use (within 1 week) is highly recommended.