Midterms 6

• Enzyme

  A compound, usually a protein, that acts as a catalyst for a biochemical reaction
• Enzymes

  • Cause cellular reactions to occur millions of times faster
  • Not consumed during the reaction but merely help the reaction occur more rapidly
  • Mostly are globular proteins
  • Provide the information that all the protein and reactions are the same or applied in the enzymes like the denaturation enzyme
• Enzyme changes

  1. Structural aspects when the pH changes

  2. Temperature is not optimum

  3. Exposure to certain harsh chemicals

  4. Mechanical agitation such as excessive or vigorous shaking of the solution containing protein
• Enzymes

  Speed up the rate of reaction a thousand to million times without being used up<|>Increase the rate of biochemical reaction
• Catalyzed reaction

  Chemical reaction with the enzyme participation
• Uncatalyzed reaction


  The opposite of catalyzed reaction
• Enzymes are biological catalysts produced by the activity of living organisms
• Enzymes are responsible for different reactions in living matter, like for the synthesis, oxidation, hydrolysis, reorientation, energy release and transfer, etc.
• The life or living things are impossible without enzymes
• Medical uses of Enzymes

  • Used to diagnose and to monitor treatment of certain diseases
  • Appearance of these enzymes [CK-MB] in the blood often indicates that there is tissue damage in an organ and that cellular contents are spilling out into the bloodstream
• Enzyme structure

  • 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 or Co-enzyme


  Small molecule that cofactor the enzymes<|>Non-protein part of the conjugated enzyme
• Holoenzyme


  Biochemically active conjugated enzyme produced from an apo-enzyme and a cofactor<|>Combined apo-enzyme and cofactor entity<|>Complete set of enzymes
• Coenzyme


  Serves as a cofactor in a conjugated enzyme<|>Vitamin derivatives
• Catalytic site


  Also known as the active site where the substance binds
• Allosteric site


  Where the regulator binds
• Nomenclature and classification of enzymes

  • Named about the function of the enzyme, type of reaction catalyzed and the substrate identity
  • Suffix -ase (e.g. Urease, Sucrase, Lipase)
  • Exception: digestive enzymes (e.g. Trypsin, chymotrypsin, pepsin)
  • Type of reaction catalyzed by an enzyme is often used as a prefix (e.g. Oxidase, Hydrolase)
  • Identity of substrate and type of reaction catalyzed (e.g. Glucose oxidase, pyruvate carboxylase, succinate dehydrogenase)
• Substrate


  Substance acted upon by the enzyme; reactant in an enzyme-catalyzed reaction
• During the early days of biochemistry, when there were no system in naming enzymes have been established, the International Union of Biochemistry instituted a systematic naming scheme
• Enzyme classes

  • Oxidoreductases
  • Transferases
  • Hydrolases
  • Lyases
  • Isomerases
  • Ligases
• Oxidoreductases


  Occur simultaneously. When oxidation happens, reduction also occur. Oxidases, Dehydrogenases, and reductases falls under the oxidoreductases. The number of carbon to oxygen bonds increases, while reducing the number of carbon to hydrogen bonds. The opposite is that the number of carbon hydrogen bonds increases while carbon oxygen bonds decreases.
• Transferases


  Enzymes for transfer of specific functional group like kinases, transaminases, phosphate and amino group transfer
• Hydrolases


  Hydrolysis process [water is needed to break the bond]
• Lyases


  Also known as desmolases; responsible for removing or adding specific groups other than hydrolysis or specific groups like dehydratase for water removal; hydratase [addition of water], decarboxylase [removal of carboxyl group]
• Isomerases


  Produce compound like isomerase
• Ligases

  Catalyze the bond formation of two substrate like synthetase and carboxylase
• 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
• Enzyme-Substrate Complex


  The intermediate reaction species that is formed when a substrate binds to the active site of an enzyme
• Active site


  The center of activity of every enzyme where the catalysis happens<|>Catalysis happen only in a small area of the structure, not in the whole enzyme
• Enzyme-substrate complex


  Causes activation and interaction between the two structures leading to the conversion of substrate into a product
• 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 [dynamic]<|>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
• Enzyme specificity

  Extent to which an enzyme's activity is restricted to a specific substrate, a specific group of substrate, a specific type of chemical bond, or a specific type of chemical reaction
• Degrees of enzyme specificity

  • Absolute Specificity (catalyzes only one reaction)
  • Group Specificity (act only on molecules that have a specific functional group)
  • Linkage Specificity (act on the particular type of bond irrespective to the rest of the molecular structure)
  • Stereochemical Specificity (act on particular isomer)
• Enzyme activity


  Measures the rate at which an enzyme converts substrate to products in a biochemical reaction
• Factors affecting enzyme activity

  • Temperature
  • pH
  • Substrate Concentration
  • Enzyme Concentration
• Temperature

  Measure of kinetic energy of molecules<|>Higher temperature mean molecules are moving faster and colliding more frequently
• Optimum temperature


  Temperature at which an enzyme exhibits maximum activity
• Group-specific enzymes


  Enzymes that have a specific functional group, such as hydroxyl, amino or phosphate groups