Unit C Enzymes

Biology

BiologyUnit C: EnzymesEnzymesBiological catalysts that increase the rate of reaction by lowering the activation energyRemain unchanged at the end of the reactionSoluble globular protein coiled into a precise 3D shapeWith hydrophilic R groups on the outside of the molecule2 types of metabolic reactionsAnabolism (condensation) build up complex moleculesCatabolism (hydrolysis) break down complex molecules

Mode of ActionEnzymes increase the rate of reaction by lowering the activation energyEnzymes active site has a specific 3D shape as wells as distribution of charges that are complementary to the subtrateSubstrate binds to the active site by lock and key method to form enzyme-substrate complexOnce the reaction has finished, the product leaves the active site and the enzyme is free to be used againpH and Enzyme activityEnzymes work in a limited pH rangeA change in pH alters the distribution of charges and the 3D shape of the enzymeThis is because H+ can interact with the R groups of amino acids by affecting the ionisation of the groupsWhich in turn affects the ionic and/or hydrogen bonding between themThe change of shape of the active site means that the substrate can no longer fit the active siteHence, extreme pH change can denatures the enzymeEnzyme InhibitorBlocks access for substrateFewer successful enzyme-substrate collisionsThis reduces the rate of reaction

Competitive InhibitorNon-Competitive InhibitorSimilar structure with substrateNo structural similarity with substrateBound only to the active siteBound to the active site or other parts of the enzymes (allosteric site)Inhibition can be reduced by adding more substrateInhibition cant be reducedBound is temporary and reversibleBonding is irreversible if attached to active site but is reversible if binds to allosteric siteDoes not change the conformation of the enzymeChanges the conformation of the enzyme