Load Closed
When the page first loads you are shown the open form of
the enzyme. The molecule shown here is the closed form, which occurs when
substrate sites in both domains are occupied. ADP and 3PGA are shown. Note
that this is a "dead-end" complex. They represent one substrate and one
product: no transfer can occur between them. For this reason, these two
were chosen deliberately to trap a closed form of the enzyme. If the real
substrates, ADP and 1-3 PGA had been used, the reaction would take place
and we would have an equilibrium mixture of substrates and products. Hit
the "Load Open" button to see the open form again. You can "animate" the
domain closure by toggling between the two buttons.
[Close]
Load Open
Open conformation is shown. Positions of ADP and 3PGA are
shown as they are found in separate complexes ( of course, together they
would spring the enzyme to close. Both would not be found together in an
open conformation of the enzyme, as here).[Close]
Hinges
Sections of the polypeptide chain that act as hinge regions
between domains are highlighted in green, magenta and red.
[Close]
Display residues that stabilise the transition
state
Arg 39 and Lys 219, which stabilise the transition state,
are shown in the closed conformation of the enzyme
[Close]
Display ADP.Pi and 3PGA
Here the ligand positions are shown for ADP and inorganic
phosphate from one structure and 3PGA from another. This is a model for
the transition state in which the inorganic phosphate can be considered
to be about to be transferred from ATP to 3PGA. The residues R39
and K219 are close enough to stabilise the pentavalent intermediate that
develops on the transferring phosphate group as this occurs.[Close]
Display transition state
This is a close up of the last view but without the protein
except for R39 and K219. A magnesium ion, which also stabilises the transition
state is shown as a green sphere.
[Close]
Spin y
Spin molecule through 360 degrees about vertical axis
[Close]