Stereo view of the active-site region of unliganded human α-thrombin.

<p>Thrombin residues are represented as thin lines (carbon depicted in cyan, oxygen in red, nitrogen in blue and sulfur in yellow). The side chains of Lys60F and Asp189 (carbon represented in pink, other elements as above), and of Asp102, His57 and Ser195 (carbon represented in yellow, other elements as above) are shown as stick models.