Four states of tyrosine residues in the fibrinogen molecule.
The ionization of tyrosine residues in fibrinogen was studied by a spectrophotometric method. The total of 100 tyrosine residues in the fibrinogen molecule was classified into four states: (1) 28 tyrosine residues with pK 10.1 (m = 1.0). (2) tyrosine residues with pK 11.5 (m = 1.0), (3) 20 tyrosine residues with pK 12.2 (m = 3.0) and (4) 10 tyrosine residues non-ionizable. When fibrinogen was treated with 4 M guanidine . HCl, all of the tyrosine residues became ionizable with the ionization characteristics of pK 10.1 (m = 1.0). The ionization characteristics of tyrosine residues in plasmin-digested fibrinogen were similar to those of fibrinogen, while in CNBr-treated fibrinogen they were fairly different. The value, m, stands for the number of hydroxyl ions involved in the ionization of a tyrosine residue.
D005340:Fibrinogen; D006146:Guanidines; D006801:Humans; D007526:Isoelectric Point; D010446:Peptide Fragments; D011489:Protein Denaturation; D013056:Spectrophotometry, Ultraviolet; D014443:Tyrosine
D006146:Guanidines; D010446:Peptide Fragments; D014443:Tyrosine; D005340:Fibrinogen