Selective tryptophan modification with rhodium carbenoids in aqueous solution.
A new transition metal-based reaction has been developed for the selective modification of tryptophan residues on protein substrates. After activation of vinyl-substituted diazo compounds by Rh2(OAc)4, the resulting metallocarbenoid intermediates were found to modify indoles in aqueous media despite competing reactions with water. Both N- and 2-substituted indole products were observed in the reaction. Following initial small-molecule studies, the reaction was performed on two protein substrates. Both myoglobin and subtilisin Carlsberg were modified readily in aqueous solution, and the tryptophan selectivity of the reactions was confirmed through MS analyses of trypsin digest fragments. It was also demonstrated that myoblobin concentrations as low as 10 muM still led to appreciable levels of modification. Reconstitution experiments confirmed that myoglobin retained its ability to bind heme following modification.
Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA.
John M
JM
Antos
Matthew B
MB
Francis
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry; D001430:Bacteriocins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009211:Myoglobin / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry; D012238:Rhodium / Q000737:chemistry*; D012862:Skatole / Q000031:analogs & derivatives*; D012996:Solutions; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014364:Tryptophan / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D001426:Bacterial Proteins; D001430:Bacteriocins; D009211:Myoglobin; D009942:Organometallic Compounds; D010455:Peptides; D012996:Solutions; D014867:Water; D014364:Tryptophan; D012862:Skatole; D012238:Rhodium; C002836:subtilin