Enzyme
Definition:
An enzyme is a biological catalyst that speeds up a cellular reaction, without being consumed in the process. Enzymes are typically proteins which bind with high specificity to their substrate(s).
Relevance:
In pharmacology, enzymes play an important role in metabolizing drugs and xenobiotics.
Enzymes regulate most of our bodily reactions, and without them, the reactions would take substantially longer. For example, enzymes catalyse microprocesses such as cellular respiration and metabolism, as well as macroprocesses such as food digestion, when large molecules such as proteins, carbohydrates, and fats are broken down into smaller molecules.
Additionally, alterations in enzymes’ function, production, and structure underly the pathogenesis of several diseases. Examples include the genetically heritable diseases albinism and phenylketonuria, which are characterized by enzyme deficiencies.
Given the role of enzymes mediating physiological and pathological processes, many drugs target enzymes to elicit the desired therapeutic effect. One example of a drug that targets an enzyme is rosuvastatin. This statin inhibits the HMG-CoA reductase, an enzyme involved in the synthesis of cholesterol.
Enzymes are essential for life; thus, dysregulated enzyme activity can cause diseased states. For example, mutations in genes that code for enzymes can result in reduced enzyme levels or decreased enzymatic activity, leading to decreased levels of product, which can further lead to pathologies.
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Compound
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Target Enzyme
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Clinical Use
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Fluorouracil
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Thymidylate Synthase
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Cancer
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Methotrexate
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Dihydrofolate Reductase
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Cancer
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Moclobemide
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Monoamine Oxidase
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Depression
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Sildenafil
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Phosphodiesterase
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Erectile Dysfunction
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Carbidopa
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Dopa Decarboxylase
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Parkinson’s Disease
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Table adapted from: Copeland, R. A. (2013). Evaluation of enzyme inhibitors in drug discovery: A guide for medicinal chemists and pharmacologists (2nd ed). Wiley.
Teaching Tips:
https://youtu.be/qgVFkRn8f10
Linked terms: Catalyst, Chemical Reaction, Protein, Rate of Reaction, substrate, metabolism, biotransformation
Resources:
Enzyme. National Human Genome Research Institute. (2023, November 7). https://www.genome.gov/genetics-glossary/Enzyme
Copeland, R. A. (2013). Evaluation of enzyme inhibitors in drug discovery: A guide for medicinal chemists and pharmacologists (2nd ed). Wiley.
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