The EGF-like domain consists of two small two stranded
beta pleated sheets. Maybe you are wondering: "Why
isn't that portion of PGHS just hanging (as shown in the
current view) straight down?" The EGF-like domain is
held to the main body by a disulfide bond.
click here >>
The portion of PGHS that remains pink is the large globular catalytic domain. This domain contains the peroxidase and cyclooxygenase active sites.
view the peroxidase active site click here>>
GREEN - inside of these green boundaries is the haem, the active site.
RED - these seven residues partly enclose the peroxidase active site, however the solvent has access to the haem.
YELLOW - this ten residue curve sticks out from the enzyme's surface forming two small binding sites for PGG2 and the reducing substrate.
In the peroxidase reaction, the haem is oxidized and the substrate - PGG2 or other long fatty chain acids - is reduced. The output is PGH2.
To see another view, click here>>
This view shows how the RED residues enclose the site, but not entirely.
The peroxidase site started with PGG2...Where did that come from?
let's move to the cyclooxygenase active site. click here>>
Imagine that the bottom right of the black screen is the outside of a cell. The hydrophobic portions of the membrane binding motif are in white and are embedded in the membrane. This serves as the entrance from the inside of the cell to the cyclooxygenase active site for hydrophobic fatty acids.
TEAL - The Serine that aspirin acetylates to decrease inflammation. This blocks access to the upper part of the channel where the active site is located.
RED ORANGE - The Tyrosine is the farthest end of the channel. This area is the cyclooxygenase active site.
In the cyclooxygenase reaction, arachidonic acid is converted to PGG2. You can see that this active site is very close to the peroxidase active site. Once PGG2 is produced in the cyclooxygenase site, it is passed to the peroxidase site and there converted into prostaglandin H2. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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