A biological catalyst produced in cells and capable of speeding up and specifying chemical reactions essential for life. A globular protein, it is specific to a particular reaction or group of similar reactions, and therefore there are a great number of them. The exact mechanism by which enzymes act is not fully understood, but it seems that certain parts of the enzyme molecule (the ‘active centers’) combine with a substrate molecule so that the substrate undergoes chemical changes much more rapidly than in the absence of the enzyme, but the enzyme itself remains unchanged. Most enzymes have the suffix -ase, which is added to the names of the substrate they act on. Thus, lactase is the enzyme that acts to break down lactose.
See Acetylcholinesterase (AcHE), Acrosome, Biochemistry, Central dogma of molecular biology, Co-factor, Collagen, Emphysema, Enzyme, Krebs cycle (or tr-carboxylic acid, TCA, cycle), Lactose intolerance, Lysosomes, Methylation, Mitochondria, Mucins, Neurotransmitters, Organelles, Pancreas, Peptides, Phosphorylation, Protein tyrosine kinase, Proteins