Chemistry · Ch 16 — Chemistry in Everyday Life
Catalytic action of enzymes
16.2.1(a)
Catalytic action of enzymes
How an Enzyme Binds and Acts on Its Substrate
An enzyme's catalytic power depends on a specific three-dimensional pocket on its surface called the active site, into which the substrate molecule fits. Two distinct chemical jobs are performed at this active site:
- Holding the substrate in the correct orientation. The active site anchors the substrate through a combination of non-covalent forces - ionic bonding, hydrogen bonding, van der Waals forces and dipole-dipole interactions - so that the substrate is presented in exactly the geometry needed for the reaction to proceed efficiently.
- Carrying out the chemical transformation. Certain functional groups projecting from the active site can themselves directly attack the substrate, breaking and forming bonds to convert it into product. …
Figure 16.1(a) Active site of an enzyme (b) Substrate (c) Substrate held in active site of the enzyme
What this figure shows. Three-panel schematic in block/wedge style (purple = enzyme, pink = substrate). Panel (a) 'Enzyme' shows a purple 3-D block with a V-shaped notch labelled 'Active site' (dashed outline marks the notch region). Panel (b) 'Substrate' shows a separate pink trapezoidal wedge. Panel (c) 'Enzyme holding substrate' shows the pink wedge fitted snugly into the purple block's V-notch, illustrating the substrate held in the enzyme's active site. …