title: Fluorescence of buried tyrosine residues in proteins.
abstract: Histone H1 contains only one tyrosine and no tryptophan. The intrinsic fluorescence of the tyrosine rises by about 400% as the protein folds from a random coil to a globular structure (Giancotti, V., Fonda, M. and Crane-Robinson, C. (1977) Biophys. Chem. 6, 379-383). Measurements of external quenching by a large variety of quenchers shows very much reduced quenching in the folded state as compared to the disordered. It is concluded that the tyrosine is a buried residue. This is supported by the observation that the fluorescence of modified amino-tyrosyl H1 is similar to that of buried tyrosines in ribonuclease. The classification of tyrosine fluorescence in tryptophan-free proteins (Cowgill, R.W. (1976) in Biochemical Fluorescence Concepts, Vol. 2 to include the case of residues buried in a hydrophobic environment and having a relative quantum yield RTyr, greater than unity.
mesh_terms: D000818:Animals; D002417:Cattle; D006657:Histones / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy; D013050:Spectrometry, Fluorescence; D013950:Thymus Gland / Q000378:metabolism; D014443:Tyrosine / Q000302:isolation & purification*
chemical_list: D006657:Histones; D014443:Tyrosine