US Patent 8242058 Reagents and methods for appending functional groups to proteins

Methods and reagents for site-selective functionalization of peptides and proteins. The methods most generally involve the reaction of a thioester with hydrazine. Reagents include bifunctional reagents of formula:H2N—NH—CH2-M-L-FGand salts thereof where M is a single bond or a chemical group carrying a non-bonding electron pair, such as —C(O)NR′—, where R′ is H, or an alkyl or aryl group; L is an optional linker group as described above; and FG is a functional group having reactivity that is orthongonal to that of the hydrazine group. FG can, among others, be an azide, alkenyl, alkynyl, nitrile (—CN) or triazole group and is preferably an azide group (—N3). Methods and reagents can, for example, be combined with intein-mediated protein splicing to link proteins or fragments thereof to various chemical species or to a surface. Surface immobilization of proteins via the methods herein results in immobilized proteins which substantially retain biological activity and is thus useful for the generation of peptide or protein microarrays. Kits for functionalization and/or immobilization of peptides and proteins are provided as well as microarrays of peptides, proteins or both.