title: Site-specific protein transamination using N-methylpyridinium-4-carboxaldehyde.
abstract: The controlled attachment of synthetic groups to proteins is important for a number of fields, including therapeutics, where antibody-drug conjugates are an emerging area of biologic medicines. We have previously reported a site-specific protein modification method using a transamination reaction that chemoselectively oxidizes the N-terminal amine of a polypeptide chain to a ketone or an aldehyde group. The newly introduced carbonyl can be used for conjugation to a synthetic group in one location through the formation of an oxime or a hydrazone linkage. To expand the scope of this reaction, we have used a combinatorial peptide library screening platform as a method to explore new transamination reagents while simultaneously identifying their optimal N-terminal sequences. N-Methylpyridinium-4-carboxaldehyde benzenesulfonate salt (Rapoport's salt, RS) was identified as a highly effective transamination reagent when paired with glutamate-terminal peptides and proteins. This finding establishes RS as a transamination reagent that is particularly well suited for antibody modification. Using a known therapeutic antibody, herceptin, it was demonstrated that RS can be used to modify the heavy chains of the wild-type antibody or to modify both the heavy and the light chains after N-terminal sequence mutation to add additional glutamate residues.
authors.affiliation: Department of Chemistry, University of California , Berkeley, California 94720-1460, United States.
authors.forename: Leah S
authors.initials: LS
authors.lastname: Witus
authors.forename: Chawita
authors.initials: C
authors.lastname: Netirojjanakul
authors.forename: Kanwal S
authors.initials: KS
authors.lastname: Palla
authors.forename: Ellen M
authors.initials: EM
authors.lastname: Muehl
authors.forename: Chih-Hisang
authors.initials: CH
authors.lastname: Weng
authors.forename: Anthony T
authors.initials: AT
authors.lastname: Iavarone
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Francis
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D000586:Amination; D000595:Amino Acid Sequence; D018698:Glutamic Acid / Q000737:chemistry; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry / Q000276:immunology; D007202:Indicators and Reagents; D008958:Models, Molecular; D019151:Peptide Library; D010455:Peptides / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D011726:Pyridinium Compounds / Q000737:chemistry*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology
chemical_list: D000447:Aldehydes; D018698:Glutamic Acid; D007074:Immunoglobulin G; D007202:Indicators and Reagents; D019151:Peptide Library; D010455:Peptides; D011506:Proteins; D011726:Pyridinium Compounds; D018719:Erb-b2 Receptor Tyrosine Kinases; C014677:1-methylpyridinium; C508053:ERBB2 protein, human