In the context of the provided reference, a PPI refers to a Proton Pump Inhibitor, a type of compound that irreversibly inhibits the proton pump (specifically, the ATPase enzyme) by forming a covalent disulfide bond with it.
Here's a breakdown:
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Proton Pump Inhibitors (PPIs): These are a class of drugs that work by reducing the production of acid in the stomach.
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Mechanism of Action (based on the reference):
- Unlike H2 antagonists that bind reversibly, PPIs interact with the ATPase enzyme, the proton pump responsible for acid secretion.
- They form a covalent disulfide bond with the enzyme (specifically, with a cysteine residue like CYS822 mentioned in the provided text).
- This covalent bond leads to irreversible inhibition of the proton pump. This means the pump is permanently disabled until new enzyme molecules are synthesized by the body.
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Activation Time: The reference suggests that PPIs with slower activation rates may have more time to react with specific amino acids like CYS822.
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Contrast with H2 Antagonists: It's important to note the difference between PPIs and H2 antagonists. H2 antagonists work by competitively and reversibly binding to H2 receptors, thus reducing acid secretion. PPIs, on the other hand, directly and irreversibly inhibit the proton pump itself.
In summary, in this context, PPIs are drugs that act as irreversible inhibitors of proton pumps by forming a covalent bond with the pump enzyme. This action decreases acid production in the stomach.
