Caspase-3 Regulatory Mechanisms: Difference between revisions
No edit summary |
No edit summary |
||
| Line 19: | Line 19: | ||
== Caspase-3 Loop Bundle and Active Site== | == Caspase-3 Loop Bundle and Active Site== | ||
=== Importance of Loop Orientation=== | === Importance of Loop Orientation=== | ||
Caspases are extremely dependent on the orientation and geometry of their active site loops. If the loops are not ordered properly the enzyme fails to function. Caspase-3 has four active site loops on each half of the dimer constituting the active site bundle. Proteolytic activity is dependent on cleavage of an intersubunit linker, which releases loop 2 (L2) and L2’. <scene name='Caspase-3_Regulatory_Mechanisms/Scene2_nospin_labels/1'>L2'(green spheres) interacts with the opposite half of the dimer by holding up L2 (blue spheres) </scene>. This allows L2 to make critical contacts with L3 and L4, allowing them to organize the active site, bind substrate, and orient the nucleophilic cysteine 163 (bright green) so that it can cleave after aspartate residues. | Caspases are extremely dependent on the orientation and geometry of their active site loops. If the loops are not ordered properly the enzyme fails to function. Caspase-3 has four active site loops on each half of the dimer constituting the active site bundle. Proteolytic activity is dependent on cleavage of an intersubunit linker, which releases loop 2 (L2) and L2’. <scene name='Caspase-3_Regulatory_Mechanisms/Scene2_nospin_labels/1'>L2'(green spheres) interacts with the opposite half of the dimer by holding up L2 (blue spheres) </scene>. This allows L2 to make critical contacts with L3 and L4, allowing them to organize the active site, bind substrate, and orient the nucleophilic cysteine 163 (bright green) so that it can cleave after aspartate residues. | ||