TCO-PEG4-acid is a click chemistry linker containing a TCO (trans-cycloctene) and a terminal carboxylic acid. The terminal carboxylic acid can react with primary amine groups in the presence of activators such as EDC. , TCO reagent is highly reactive with tetrazine in an inverse electron demand Diels Alder (IEDDA) reaction followed by a retro-DA reaction. The hydrophilic PEG spacer increases solubility in aqueous media. Reagent grade, for research purpose. Please contact us for GMP-grade inquiries.