BB1-NHS ester is amine reactive at pH 7-9 to form a stable, irreversible amide bond. It was used in a unique chemselective "unclickable' bioconjugation strategy to site specifically modify proteins.nRef: P. Andy, S. ERickson, J. Italia, A. Chatterjee, JACS, 2017, 139 (34), 11670-11673 Reagent grade, for research purpose. Please contact us for GMP-grade inquiries.