Mechanisms of Enzyme Regulation
| Mechanism | Description |
|---|---|
| Allosteric Regulation | Effector molecules bind to a site other than the active site, inducing a conformational change that increases or decreases activity. |
| Covalent Modification | Reversible addition of groups, most commonly phosphorylation/dephosphorylation (e.g., via kinases and phosphatases). |
| Proteolytic Activation | Irreversible activation by cleaving an inactive precursor (zymogen or proenzyme), such as pepsinogen to pepsin. |
| Feedback Inhibition | The end product of a metabolic pathway inhibits an upstream rate-limiting enzyme, preventing overproduction. |
High-Yield Core Realities:
- Zymogens: Important for digestive enzymes (like trypsinogen) and the coagulation cascade to prevent premature, uncontrolled activation.
- Allosteric Kinetics: Allosteric enzymes often show a sigmoidal (S-shaped) curve rather than the classic Michaelis-Menten hyperbolic curve, reflecting cooperativity between subunits.
- Metabolic Control: Cells often utilize a combination of these mechanisms to maintain homeostasis, particularly in pathways like glycolysis, where Phosphofructokinase-1 (PFK-1) is tightly regulated.