title: Comparative study of the iodination of tyrosines in the amino terminal domain of fibrinogen and in N-DSK and fibrin-N-DSK.
abstract: Lactoperoxidase catalyzed iodination has been used to probe for differences in surface orientation of tyrosine residues in the amino-terminal disulfide knot (N-DSK) domain of fibrinogen, in N-DSK and in Fb-N-DSK prepared from fibrin. The central region of N-DSK containing the beta chain Tyr 41 and gamma chain Tyr 18 and 32 are much more susceptible to iodination than when an integral part of the fibrinogen molecule. Cleavage of the N-DSK domain from fibrinogen "loosens" up the tertiary structure of N-DSK and allows iodination of its central region. The iodination pattern of comparable tyrosine residues did not change between N-DSK and Fb-N-DSK. This result implies that no significant change occurs in the tertiary structure of N-DSK upon thrombin activation. These results favor the concept that removal of the fibrinopeptides removes a steric hindrance or exposes a binding site for polymerization.
mesh_terms: D000595:Amino Acid Sequence; D055598:Chemical Phenomena; D002621:Chemistry; D004220:Disulfides; D005337:Fibrin; D005340:Fibrinogen; D005344:Fibrinopeptide A; D006801:Humans; D066298:In Vitro Techniques; D007455:Iodine / Q000378:metabolism; D007457:Iodine Radioisotopes; D007553:Isotope Labeling; D007784:Lactoperoxidase; D013329:Structure-Activity Relationship; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D004220:Disulfides; D007457:Iodine Radioisotopes; D005344:Fibrinopeptide A; D014443:Tyrosine; D005337:Fibrin; D005340:Fibrinogen; D007455:Iodine; D007784:Lactoperoxidase