Rotate:
  X 90°   X -90°
  Y 90°   Y -90°

  Distances:
  Height (Å units)
  Width (Å units)

  Display Conformations:
  "Closed", only
  "Open", only
  Open & Closed

  Highlight Loops:
  Closed Conformation
  Open Conformation

  Glucose Binding Site:
  Closed Conformation
      H-Bonds
  Open Conformation

  Remove labels
  Reset

The "Display Conformations" buttons switch between the two models. Each chain can also be selected individually using the Chime menu under "Model".

The "Highlight Loops" buttons color the four loops in the small domain that close in on the bound substrate. Loops 1-4 are colored cyan, green, magenta and yellow, respectively in each conformation.

The "Glucose Binding Site" buttons display the following:

The Closed Conformation zooms to show glucose and the amino acid side chains that are within H-bonding distance. The carbon positions of glucose are numbered; the amino acids are labeled at CA.

The Open Conformation shows the equivalent amino acids in the yeast enzyme. The space that is occupied by glucose in the closed confromation is represented here by a Dot Surface.

Most of the contacting side chain locations are the same in the two conformations, however, Thr 175 and Lys 176 in Loop 4 move ~9 Å to donate H-bonds to glucose in the closed conformation.

The "Open" structure (1ig8.pdb) is of the yeast enzyme; the "Closed" structure (1bdg.pdb) is of the Shistosoma mansoni enzyme. When the amino acid sequence of yeast hexokinase is aligned with that of S. mansoni, the amino acids are identical at only 30% of the positions. However, the structures of the two domains align to within about 2.0 Å.

The yeast hexokinase structure and the comparison to the S. mansoni enzyme is described in Kuser, P. R., Krauchenco, S., Antunes, O. A., Polikarpov, I. (2000) "The High Resolution Crystal Structure of Yeast Hexokinase PII with the Correct Primary Sequence Provides New Insights Into its Mechanism of Action." J.Biol.Chem. 275 20814.     PubMed.