Detailed Explanation
An enzyme is a biological catalyst — a molecule that dramatically speeds up a chemical reaction without being consumed in the process. Almost all enzymes are proteins, though some RNA molecules (ribozymes) also have catalytic activity. Enzymes are central to peptide biology because they build peptides (ribosomes), modify them (kinases, acetyltransferases), and destroy them (proteases). The human genome encodes approximately 20,000 proteins, of which several thousand function as enzymes.
Enzymes achieve their catalytic power through precise three-dimensional active sites that bind substrates with high specificity — the lock-and-key or induced-fit model. They lower the activation energy of reactions by factors of 10⁶ to 10¹² compared to uncatalyzed rates. Key enzyme classes in peptide science include proteases (cleave peptide bonds — trypsin, DPP-IV, ACE), kinases (add phosphate groups — ~518 in the human 'kinome'), phosphatases (remove phosphates), and transferases (move chemical groups between molecules).
For peptide drug development, enzymes are both obstacles and targets. Proteolytic enzymes like DPP-IV rapidly destroy native GLP-1 (half-life ~2 minutes), which is why GLP-1 drugs must be engineered for protease resistance. Conversely, enzyme inhibitors are major drug classes: ACE inhibitors (captopril, lisinopril) for hypertension, DPP-IV inhibitors (sitagliptin, saxagliptin) for diabetes, and HIV protease inhibitors for AIDS are all designed to block specific enzymes.
Key Facts
- Almost all enzymes are proteins; some are RNA (ribozymes)
- Speed up reactions by factors of 10⁶ to 10¹²
- Human kinome: ~518 kinases regulating cellular signaling
- DPP-IV destroys GLP-1 in ~2 minutes — key target for diabetes drugs
- ACE inhibitors, DPP-IV inhibitors, HIV protease inhibitors are all enzyme-targeted drugs
- Enzymes are named by substrate + '-ase' suffix (protease, kinase, lipase)
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PeptideDefinition.com provides educational content about peptide science. Not medical advice. Consult a licensed healthcare provider for medical decisions.