title: Photosensitized labeling of solvent-exposed parts of proteins. Studies on fibrinogen and the fibrinogen-fibrin conversion.
abstract: A new technique for surface labeling of biological structures based on dye-sensitized photochemical coupling of labeled low molecular weight substances has been applied to studies on fibrinogen. When a solution of fibrinogen containing fluorescein and 3H-labeled tryptophan was illuminated with visible light, radioactive labeling of fibrinogen occurred in proportion to the illumination time. Determination of the relative labeling of the various peptide chains after reduction and separation by polyacrylamide gel electrophoresis showed the following labeling pattern; alpha : beta : gamma = 2.7 : 1.0 : 1.0, suggesting that the alpha chain is relatively more exposed to solvent than the other chains. When the illumination was performed in the presence of urea the labeling pattern was changed to 1.0 : 1.9 : 1.5, showing that the labeling is sensitive to conformation. When fibrinogen was transformed to fibrin and then labeled the labeling ratio was 3.0 : 1.3 : 1.0.
mesh_terms: D005337:Fibrin / Q000378:metabolism / Q000528:radiation effects*; D005340:Fibrinogen / Q000378:metabolism / Q000528:radiation effects*; D005452:Fluoresceins; D006801:Humans; D008027:Light; D010777:Photochemistry; D011487:Protein Conformation; D013917:Thrombin / Q000378:metabolism; D014364:Tryptophan
chemical_list: D005452:Fluoresceins; D014364:Tryptophan; D005337:Fibrin; D005340:Fibrinogen; D013917:Thrombin