enzymology

Enzymology is the branch of biochemistry that studies enzymes, the biological catalysts that accelerate chemical reactions in living organisms. Most enzymes are proteins, though some RNA molecules also have catalytic activity, known as ribozymes. Enzymology examines how enzymes function, how they are regulated, and how their activities are integrated into cellular processes.

Enzymes work by lowering the activation energy of a reaction and by providing an active site with a specific shape and chemical environment. Substrates bind to the active site, often undergoing conformational changes (induced fit) to form products. Specificity is a hallmark: enzymes typically act on particular substrates or classes of substrates. Many enzymes require cofactors, such as metal ions or organic molecules (coenzymes) like NAD+, FAD, or CoA, to participate in catalysis.

Kinetics describe how enzyme rate depends on substrate concentration. The Michaelis-Menten model introduces parameters Km and Vmax; the turnover number kcat quantifies catalytic efficiency. Enzyme activity is regulated by factors including temperature, pH, and inhibitors. Allosteric regulation, covalent modification, and proteolytic activation are common control mechanisms, enabling metabolic pathways to respond to cellular needs.

Structurally, enzymes have defined three-dimensional shapes that position catalytic residues within the active site. Higher-resolution methods such as X-ray crystallography and cryo-electron microscopy reveal active-site geometry. Enzyme assays measure activity using colorimetric, fluorometric, or radiometric readouts. Purification and characterization are essential for mechanistic studies and applications.

Historically, enzymology emerged from work on fermentation and digestion, with contributions from Buchner and others, and the concept of enzyme specificity developed by Fischer. Today, enzymology supports fields ranging from medicine and industrial biotechnology to environmental science, including drug design, diagnostic assays, and the production of biocatalysts for sustainable chemistry.