Shinichi Sato , Kosuke Nakamura , and Hiroyuki Nakamura * Chemical Resources Laboratory, Tokyo Institute of Technology , Yokohama 226-8503, Japan ACS Chem. Biol. , Article ASAP DOI: 10.1021/acschembio.5b00440 Publication Date (Web): September 10, 2015 Copyright © 2015 American Chemical Society *E-mail: hiro@res.titech.ac.jp. http://pubs.acs.org/doi/10.1021/acschembio.5b00440 Abstract Tyrosine-specific chemical modification was achieved using in situ hemin-activated luminol derivatives. Tyrosine residues in peptide and protein were modified effectively with N-methylated luminol derivatives under oxidative conditions in the presence of hemin and H 2 O 2 . Both single and double modifications of the tyrosine residue occurred in the reaction of angiotensin II with N-methylated luminol derivative 9 . Tyrosine-specific chemical modification of the model protein bovine serum albumin (BSA) revealed that the surface-exposed tyrosine residues were selectivel...