Tyrosinase-induced cross-linking of tyrosine-containing peptides investigated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.
Tyrosinase-induced oxidation of tyrosine is known to lead to melanin by cross-linking of 5,6-dihydroxyindole (DHI) and indole-5,6-quinone intermediates. However, tyrosinase-induced cross-linking of tyrosine-containing peptides has not been reported. We observed tyrosinase-induced adducts of tyrosine-containing peptides by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). MALDI-TOFMS was also used to observe tyrosine adducts at various levels of oxidation derived from acid hydrolysis of the peptide adducts. The rate of tyrosinase-induced browning of lys-tyr-lys was about half of that of tyrosine. These results indicate that tyrosinase-induced browning of tyrosine-containing peptides via direct oxidation and cross-linking of the benzene ring of the tyrosine residue occurs at a significant rate and needs to be considered in melanogenesis.
School of Chemistry, Seoul National University, Seoul 151-747, South Korea.
J G
JG
Jee
S J
SJ
Park
H J
HJ
Kim
D000595:Amino Acid Sequence; D003432:Cross-Linking Reagents; D014442:Monophenol Monooxygenase / Q000494:pharmacology*; D010455:Peptides / Q000032:analysis* / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014443:Tyrosine / Q000032:analysis*
D003432:Cross-Linking Reagents; D010455:Peptides; D014443:Tyrosine; D014442:Monophenol Monooxygenase