Figure 2.
Fig 2. Crystallographic structure of the HCII-thrombin
Michaelis complex. (a) A stereo representation of the Michaelis
complex between S195A thrombin (cyan) and HCII (colored as
described for Fig. 1), with the -loop in front and the
60-insertion loop behind the reactive center loop. (b) Stereo
representation of the electron density covering the portion of
the acidic tail (yellow) that interacts with thrombin (magenta),
contoured at 1 . (c) The subsite
interactions between the reactive center residues of HCII (rods)
and the active site cleft of thrombin (surface representation)
are extensive and complementary in both electrostatic (Left,
negative potential is red, and positive is blue) and hydrophobic
(Right, green for hydrophobic side chains) properties. (d) The
interaction between exosite I of thrombin (surface
representation as described for c) and the hirudin-like
N-terminal tail of HCII (rods, the side chains of residues not
interacting with thrombin were removed for clarity) is primarily
hydrophobic. The only ionic interactions are between Asp-70 and
Asp-72 of HCII and L110H of thrombin. Sulfated tyrosines, 60 and
73, make no contacts with thrombin and are not shown.
-loop in front and the
60-insertion loop behind the reactive center loop. (b) Stereo
representation of the electron density covering the portion of
the acidic tail (yellow) that interacts with thrombin (magenta),
contoured at 1 
. (c) The subsite
interactions between the reactive center residues of HCII (rods)
and the active site cleft of thrombin (surface representation)
are extensive and complementary in both electrostatic (Left,
negative potential is red, and positive is blue) and hydrophobic
(Right, green for hydrophobic side chains) properties. (d) The
interaction between exosite I of thrombin (surface
representation as described for c) and the hirudin-like
N-terminal tail of HCII (rods, the side chains of residues not
interacting with thrombin were removed for clarity) is primarily
hydrophobic. The only ionic interactions are between Asp-70 and
Asp-72 of HCII and L110H of thrombin. Sulfated tyrosines, 60 and
73, make no contacts with thrombin and are not shown.