ENZYMES

• ENZYMES are catalysts and are not consumed in the reactions
• SIMPLE ENZYME: composed only of protein (amino acid chains)
• CONJUGATED Enzyme: has a nonprotein part in addition to a protein part
• APOENZYME: Protein part of a conjugated enzyme.
• COFACTOR: Nonprotein part of a conjugated enzyme.
• HOLOENZYME: the biochemically active conjugated enzyme
• Co-enzymes are derived from dietary vitamins
• Inorganic ion cofactors derived from dietary minerals
• Substrate is the reactant in an enzyme-catalyzed reaction:
• Oxidoreductases – Oxidation-reductions
• Transferases – Functional group transfer reaction
• Hydrolases – Hdrolysis reactions
• Lyases – Reactions involving addition or removal of groups form double bonds
• Ligases – Reactions involving bond formation coupled with ATP hydrolysis
• Isomerase – Isomerisation reactions
• OXIDATION

  it requires a coenzyme that is either oxidized or reduced as the substrate in the reaction
• Oxidoreductase - LACTATE DEHYDROGENASE
• Transferaase


  TRANSAMINASES - catalyze transfer of an amino group to a substrate
• Transferase


  KINASES - catalyze transfer of a phosphate group from adenosine triphosphate (ATP) to a substrate
• Hydrolase - protease
• Lyase - an enzyme that catalyzes the addition of a group to a double bond or the removal of a group

  to form a double bond in a manner that does not involve hydrolysis or oxidation
• Lyase - dehydratase
• Isomerase - rearrangement of atoms
• ACTIVE SITE: relatively small part of an enzyme's structure that is actually involved in catalysis
• ACTIVE SITE: Place where substrate binds to enzyme
• Lock and key - Enzyme has a pre-determined shape for the active site
• Lock and key - Enzyme has a pre-determined shape for the active site
• Induced Fit Model

  Substrate contact with enzyme will change the shape of the active site
• ABSOLUTE SPECIFICITY - An enzyme will catalyze a particular reaction for only one substrate
• ABSOLUTE SPECIFICITY - MOST RESTRICTIVE OF ALL SPECIFICITIES
• Ureases is an enzyme with absolute specificity
• STEREOCHEMICAL SPECIFICITY - An enzyme can distinguish between stereoisomers.
• GROUP SPECIFICITY -Involves structurally similar compounds that have the same functional groups.
• LINKAGE SPECIFICITY - Involves a particular type of bond irrespective of the structural features in the vicinity of the bond
• ENZYME INHIBITOR: a substance that slows down or stops the normal catalytic function of an enzyme by

  binding to it.
• COMPETITIVE INHIBITORS: Compete with the substrate for the same active sitel; Will have similar charge & shape
• NONCOMPETITIVE INHIBITORS: Do not compete with the substrate for the same active sit ; Binds to the enzyme at a location other than active site
• Competitive inhibition can be reduced by simply increasing the concentration of the substrate.
• A noncompetitive enzyme inhibitor decreases enzyme activity by binding to a site on an enzyme other

  than the active site.
• An irreversible enzyme inhibitor inactivates enzymes by forming a strong covalent bond with the

  enzyme's active site