In SituAnalysis of Peptidyl DOPA in Mussel Byssus Using Rotational-Echo Double-Resonance NMR

Rotational-echo double-resonance (REDOR)13C NMR spectra with2H dephasing have been obtained from plaques and threads from the byssus of the marine musselMytilus edulislabeled by sea-water exposure tol-[ring-4-13C]tyrosine andl-[ring-d4]tyrosine for 2 days. Specific isotopic enrichment of tyrosine in protein reached 25% in both13C and2H. Fifteen percent of the total13C label was incorporated as diphenolic carbon. Based on REDOR dephasing, about one-tenth of tyrosine rings in both intact plaques and threads are within 4 إ of each other or rings of 3,4-dihydroxyphenylalanine (DOPA). However, there is no direct evidence for the formation of covalent linkages between or among tyrosine and DOPA rings in either plaques or threads.