Molecular model of fibrinogen Philadelphia. The γ-chain C-terminal 30-kDa fragment (1FIC) was examined using Swiss-Pdb viewer. The backbone is shown in red (oxygen), white (carbon), and blue (nitrogen) with amino acid residues of interest colored as follows: the fibrinogen Philadelphia mutation (378, orange), some of the residues thought to be critical to polymerization (329, 330, 340, 364, and 375, purple), some of the residues involved in lateral aggregation (350-360, 370-380, yellow), those involved in calcium binding (318, 320, green), and some of the residues involved in D:D interactions (275 and 280, green). (A) Complete C-terminal fragment of wild-type γ chain. The purple arrow indicates region of polymerization pocket and orange arrowhead (embedded in molecule) points to the location of Ser378, the residue affected in fibrinogen Philadelphia. (B) Amino acids 350 to 380 of the wild-type γ chain with residues critical to polymerization pocket visible. (C) Most favored conformation of amino acids 350 to 380 of fibrinogen Philadelphia with residues critical to polymerization pocket visible. Note the green dotted line (0.282 nm) indicating a newly created hydrogen bond between Gly352 (in red) and Pro378.