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From Proteopedia

, or , is an enzyme that phosphorylates hexose to a hexose phosphate. In most cases, this is the phosphorylation of glucose into glucose-6-phosphate in glycolysis. Glycolysis is the process by which glucose is broken down to release the energy necessary to form ATP and NADH. Hexokinase is unique in its ability to function in aeroboic and anaerobic conditions for glycolysis. consists of mostly being on the surface and more in the interior of hexokinase. The colored space filling model found within hexokinase is glucose, the ligand in this enzyme catalyzed reaction. (This enzyme is super fabulous!)

Hexokinase with glucose, specifically at the brown sites. The gray, purple, and red atoms represent the ligand. The that interacts with the glucose (Asp205) holds it in place to ensure that it is properly phosphorylated into glucose-6-phosphate. It specifically interacts with the alcohol group that is coming off of C-6 on glucose.

Hexokinase has large amount of that stabilize the overall structure of the protein (but unfortunately, the link does not work and I am therefore unable to show the hydrogen bonds and their specific effects). Hydrogen bonding allows for the determination of whether the beta sheets are parallel or antiparallel. Parallel sheets are characterized by hydrogen bonds that are not at right angles to the sheet while antiparallel sheets are characterized by their perpendicular orientation relative to the sheets. Hexokinase does not appear to contain any disulfide linkages because it is an intercellular protein. In an intercellular environment, disulfide linkages would be reduced in the cell due to the nature of the environment.

(purple) residues and (lime green) residues are found on the inside of the protein and the outside of the protein respectively. This is the result of the protein’s interaction with the (light blue) in its environment. drives the hydrophobic residues towards the center of the protein, exposing the hydrophilic residues on the outside of the protein. These hydrophilic residues are made more obvious through the presence of water only on the surface of the enzyme. In a stick-wire frame of both the residues, it appears as if the hydrophilic (yellow) residues envelop the hydrophobic (purple) residues.