active site - the part of an enzyme or antibody where the chemical reaction occurs

ADA, adenosine deaminase - an enzyme found in mammals that can catalyze the deamination of adenosine into inosine and ammonia; "ADA deficiency can lead to one form of severe combined immunodeficiency disease"; "the gene encoding ADA was one of the earlier human genes to be isolated and cloned for study"

catalyst, accelerator - (chemistry) a substance that initiates or accelerates a chemical reaction without itself being affected

protein - any of a large group of nitrogenous organic compounds that are essential constituents of living cells; consist of polymers of amino acids; essential in the diet of animals for growth and for repair of tissues; can be obtained from meat and eggs and milk and legumes; "a diet high in protein"

amylase - any of a group of proteins found in saliva and pancreatic juice and parts of plants; help convert starch to sugar

cholinesterase - an enzyme that hydrolyses acetylcholine (into choline and acetic acid)

coagulase - an enzyme that induces coagulation

collagenase - any enzyme that catalyzes the hydrolysis of collagen and gelatin

complement - one of a series of enzymes in the blood serum that are part of the immune response

catalase - enzyme found in most plant and animal cells that functions as an oxidative catalyst; decomposes hydrogen peroxide into hydrogen and water

Cox, cyclooxygenase - either of two related enzymes that control the production of prostaglandins and are blocked by aspirin

decarboxylase - any of the enzymes that hydrolize the carboxyl group

de-iodinase - an enzyme that removes the iodine radical

disaccharidase - an enzyme that catalyzes the hydrolysis of disaccharides into monosaccharides

elastase - a pancreatic enzyme that catalyzes the hydrolysis of elastin

enterokinase - enzyme in the intestinal juice that converts inactive trypsinogen into active trypsin

histaminase - enzyme that acts as a catalyst in converting histidine to histamine

hyaluronidase, Hyazyme, spreading factor - an enzyme (trade name Hyazyme) that splits hyaluronic acid and so lowers its viscosity and increases the permeability of connective tissue and the absorption of fluids

isomerase - an enzyme that catalyzes its substrate to an isomeric form

kinase - an enzyme that catalyzes the conversion of a proenzyme to an active enzyme

lipase - an enzyme secreted in the digestive tract that catalyzes the breakdown of fats into individual fatty acids that can be absorbed into the bloodstream

lysozyme, muramidase - an enzyme found in saliva and sweat and tears that destroys the cell walls of certain bacteria

MAO, monoamine oxidase - an enzyme that catalyzes the oxidation of many body compounds (e.g., epinephrine and norepinephrine and serotonin)

nitrogenase - an enzyme of nitrogen-fixing microorganisms that catalyzes the conversion of nitrogen to ammonia

nuclease - general term for enzymes that catalyze the hydrolysis of nucleic acid by cleaving chains of nucleotides into smaller units

oxidase - any of the enzymes that catalyze biological oxidation

oxidoreductase - an enzyme that catalyzes oxidation-reduction

papain - a proteolytic enzyme obtained from the unripe papaya; used as a meat tenderizer

beta-lactamase, penicillinase - enzyme produced by certain bacteria that inactivates penicillin and results in resistance to that antibiotic

pepsin - an enzyme produced in the stomach that splits proteins into peptones

pepsinogen - precursor of pepsin; stored in the stomach walls and converted to pepsin by hydrochloric acid in the stomach

phosphatase - any of a group of enzymes that act as a catalyst in the hydrolysis of organic phosphates

fibrinolysin, plasmin - an enzyme that dissolves the fibrin of blood clots

polymerase - an enzyme that catalyzes the formation of new DNA and RNA from an existing strand of DNA or RNA

peptidase, protease, proteinase, proteolytic enzyme - any enzyme that catalyzes the splitting of proteins into smaller peptide fractions and amino acids by a process known as proteolysis

reductase - an enzyme that catalyses the biochemical reduction of some specified substance

chymosin, rennin - an enzyme that occurs in gastric juice; causes milk to coagulate

secretase - a set of enzymes believed to snip pieces off a longer protein producing fragments of amyloid protein that bunch up and create amyloid protein plaques in brain tissue (the pathological hallmark of Alzheimer's)