Enzymes

• Simple enzyme


  Composed only of protein
• Conjugated Enzyme


  Has a non - protein part in addition to a protein part
• Apoenzyme


  Protein of the conjugated enzyme
• Cofactor


  Non - protein part of the conjugated enzyme
• Holoenzyme


  Biochemically active conjugated enzyme produced from an apoenzyme and a cofactor

  
  

  Combined apoenzyme and cofactor entitiy
• Coenzyme


  Serves as a cofactor in a conjugated enzyme
• Substrate


  Reactant in an enzyme - catalyzed reaction
• Oxidoreductase


  Catalyzes an oxidation - reduction reaction.

  
  

  Requires a coenzyme that is oxidized or reduced as the substrate is reduced or oxidized
• Transferase


  Catalyzes the transfer of a functional group from one molecule to another
• Transaminases


  Catalyzes the transfer of amino group from one molecule to another
• Kinases


  Catalyzes the transfer of phosphate group from ATP to give ADP and a phosphorylated product.
• Hydrolase


  Catalyzes the hydrolysis reaction

  
  

  Central to the process of digestion

  
  

  Carbohydrases, Proteases, and Lipases
• Lyase


  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
• Isomerase


  Catalyzes the isomerisation of a substrate in a reaction converting it to a molecule isomeric with itself.

  
  

  One reactant and one product in reactions.
• Ligase


  Catalyzes the bonding together of two molecules into one with the participation of ATP.
• Enzyme active site


  Small part of an enzyme's structure that is actually involved in catalysis.

  
  

  A three - dimensional entity formed by groups that come from different parts of the protein chains
• Substrate Complex


  The intermediate reaction species that is formed when a substrate binds to the active site of an enzyme.
• Lock - and - Key Model


  Active site in the enzyme has the fixed, rigid geometrical conformation.

  
  

  Substrate with a complementary geometry can be accommodated.
• induced - Fit Model


  Enzyme's active site is not rigid and static.

  
  

  There's a constant change in shape

  
  

  Allows for changes in the shape or geometry of the active site of an enzyme to accommodate a substrate.

  
  

  Result of the enzyme's flexibility; it adapts the incoming substrate.
• Absolute Specificity


  Catalyze only one reaction

  Most restrictive of all specificities
• Catalase


  enzyme with absolute specificity
• Group Specificity


  Act only on molecules that have a specific functional group, such a hydroxyl, amino or phosphate groups.

  
  

  Carboxylpeptidase is group specific.
• Linkage Specificity


  Act on the particular type of bond, irrespective to the rest of the molecular structure.

  
  

  Phosphatases hydrolyze phosphate - ester bonds in all types of phosphate esters

  
  

  Most general of the common species
• Stereochemical Specificity


  Act on a particular isomer
• Enzyme Activity


  Measures the raste at which an enzyme converts substrate to products in a biochemical reaction
• Temperature


  Measure of kinetic energy of molecules.

  
  

  Higher ______ mean molecules are moving faster and colliding more frequently
• Optimum temperature


  Temperature at which an enzyme exhibits maximum activity
• pH


  the charge on acidic and basic amino acids located at the active site depends on __

  
  

  small __ changes can result in enzyme denaturation and subsequent loss of catalytic activity.

  
  

  Biochemical buffers help maintain the optimum __ for an enzyme.

  
  

  Can also affect substrate, causing either protonation or deprotonation of groups on the substrate.
• Optimum pH


  pH at which an enzyme exhibits maximum activity

  
  

  physiological pH ranges from 7.0 - 7.5
• Pepsin


  Active in the stomach, functions best at pH 2.0
• Trypsin


  Operates in the small intestines, function best at pH 8.0
• Substrate concentration


  Increased concentration of substrate will obtain the enzyme activity.
• Turnover number


  Number of substrate molecules transformed per minute by one molecule of enzyme uunder optimum conditions of temperature, pH and saturation.
• Enzyme Concentration


  Kept in a low number because enzymes are not consumed in the reaction.

  
  

  The greater the _______, the greater the reaction rate.
• Extremozymes


  A microbial enzyme active at a conditions that would inactivate human enzymes as well as enzymes present in other types of higher organisms
• Extremophile


  Microorganisms that thrives in extreme environments

  
  

  Acidophiles

  optimal growth at ph levels of 3.0 or below

  
  

  Alkaliphiles

  
  

  Optimal growth at pH levels of 9.0 or above

  
  

  Hyperthermophile

  
  

  Temperature between 80C and 122C needed to thrive

  
  

  Halophiles

  
  

  Cryophiles
• Acidophiles


  optimal growth at ph levels of 3.0 or below
• Alkaliphiles


  Optimal growth at pH levels of 9.0 or above
• Hyperthermophile


  Temperature between 80C and 122C needed to thrive Halophiles

  Cryophiles
• Enzyme inhibitor


  Substance that slows or stops the normal catalytic function of an enzyme by binding to it.