Kringle 4 from human plasminogen: a proton magnetic resonance study via two-dimensional photochemically induced dynamic nuclear polarization spectroscopy.
Two-dimensional (2D) proton magnetic resonance techniques used in conjunction with laser photochemically induced dynamic nuclear polarization (photo-CIDNP) spectroscopy have been applied to studying the kringle 4 domain from human plasminogen at 360 MHz. Out of 11 potential CIDNP-sensitive aromatic side chains, only 5 (His3, Tyr41, Tyr50, Trp72, and Tyr74) appear to be accessible to 3-(carboxymethyl)lumiflavin, the dye used to photogenerate spin polarization. Of these, Trp72 and Tyr74 are known to be at, or near, the lysine-binding site. The spin-spin scalar (J) and phase-sensitive dipolar (Overhauser) connectivities in the 2D experiments yield absolute assignments for the aromatic signals stemming from the exposed tyrosyl and tryptophanyl rings. Moreover, a number of side-chain H beta resonances can be identified and assigned to specific types of aromatic amino acid residues.
D000595:Amino Acid Sequence; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D010446:Peptide Fragments / Q000032:analysis; D010958:Plasminogen; D011487:Protein Conformation
D010446:Peptide Fragments; D010958:Plasminogen