Enzymes I

enzyme

globular proteins that catalyse metabolic reactions in the body

catalyst

substance that increases the rate of reaction by lowering its activation energy

substrate

reactant that an enzyme is compatible with

enzyme-substrate complex

construct formed when an enzyme and its substrate interact

metabolism

umbrella term that refers to all of the chemical reactions in the body

anabolism

the instance in which smaller molecules combine to form large, more complex molecules needed for cellular function

catabolism

the instance in which larger molecules break down into smaller, simpler molecules for the purpose of gaining energy

lock and key

relationship between an enzyme and substrate in which an enzyme is only compatible with a specific substrate

active site

pocket created by the globular structure that precisely fits the substrate

induced fit

instance in which the enzyme changes its shape to expose the parts that react with the substrate

amylase

enzyme that breaks down starch into maltose

maltase

enzyme that breaks down maltose into glucose

pepsin/trypsin

enzymes that break down proteins into polypeptides and polypeptides into amino acids

ATPase

enzymes that aid in the synthesis of ATP during aerobic respiration

caltase

enzyme that breaks down hydrogen peroxide into hydrogen and oxygen

DNA ligase

enzyme that joins two pieces of DNA molecules together

acetylcholinesterase

enzyme that breaks down acetylcholine to cease transmission of impulses

optimum temperature

temperature at which the enzyme is most efficient

optimum pH

pH at which the enzyme is most efficient

pH range

pH range in which an enzyme can function

enzyme inhibitor

a molecule which binds to enzymes and slows down or stop enzyme-catalyzed reactions

competitive inhibitors

those that have similar shapes to the substrate of the enzymes and thus bind to the active site

allosteric site

binding site addition to the active site of an enzyme

non-competitive inhibitors

those that bind to the allosteric site and alter the shape of the active site

succinate dehydrogenase

a cytoplasmic enzyme that catalyses succinate into fumarate but it often competes with oxaloacetate

aldehyde dehydrogenase (ALDH)

enzyme that converts acetaldehyde to acetic acid

alcohol dehydrogenase

enzyme that converts ethanol into acetaldehyde

antabuse

enzyme that non-competitively inhibits ALDH and allows acetaldehyde to build up in the body

organophosphates

substances that inhibit acetylcholinesterase by phosphorylating a serine residue in the enzyme’s active site which causes acetylcholine to accumulate