Chapter 7: Enzymes: Mechanism of Action

By significantly lowering activation energy, these proteins—and a few catalytic RNA molecules known as ribozymes—accelerate reaction rates by factors of one million or more while maintaining remarkable substrate specificity and stereospecificity,. The International Union of Biochemistry classifies enzymes into six major categories, including oxidoreductases, transferases, and ligases, based on the specific type of chemical transformation they facilitate,. To extend their catalytic capabilities, many enzymes utilize prosthetic groups, cofactors, or coenzymes, the latter of which frequently derive from water-soluble B vitamins and act as recyclable shuttles for chemical groups like electrons or methyl units,. Catalysis occurs within a specialized pocket called the active site, where the enzyme employs mechanisms such as proximity, acid-base interactions, transition state strain, and covalent bonding to transform substrates into products,. Moving beyond the rigid lock-and-key model, the induced fit model describes the dynamic conformational adjustments enzymes undergo upon binding to optimize the reaction environment. In clinical medicine, the detection of specific enzymes and isozymes in the blood, such as cardiac troponins for diagnosing myocardial infarction or alanine aminotransferase for liver disease, serves as a vital diagnostic and prognostic tool,. Furthermore, the chapter details how enzyme specificity is harnessed in modern biotechnology through techniques like the polymerase chain reaction (PCR), enzyme-linked immunosorbent assays (ELISA), and high-throughput screening for drug discovery,. The discovery of ribozymes has even reshaped evolutionary theory, suggesting an ancient RNA world where nucleic acids served as both genetic blueprints and catalysts. Advanced research tools like site-directed mutagenesis and affinity tagging, such as the use of histidine or GST tags, allow scientists to probe enzyme structures and purify recombinant proteins for therapeutic and industrial use,.