ENZYMES

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Author:
RolandoBijasa
ID:
305295
Filename:
ENZYMES
Updated:
2015-07-17 10:36:34
Tags:
biochem
Folders:
BioChemistry
Description:
Lesson 3: Enzymes
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  1. specialized protein with catalytic properties
    enzymes
  2. exception of proteins with catalytic properties
    ribozymes
  3. RNA's with catalytic activity (transcription)
    ribozymes
  4. properties of enzymes
    • efficient/ effective
    • very specific/ very selective in action
    • location
  5. Types of specificity
    • stereochemical
    • broad
    • absolute
    • linkage
  6. E act only on one particular isomer
    stereochemical specificity
  7. E acts on a group of structurally related compounds
    Broad
  8. acts on only one substrate
    absolute specificity
  9. act only on one king of bind or linkage
    linkage specificity
  10. peptidase -----> 1
    carbohydrase -----> 2
    esterase -----> 3
    phosphatase -----> 4
    • 1 peptide bond
    • 2 glycosidic bond
    • 3 ester bond
    • 4 phosphate ester bond
  11. activities of this enzyme can be controlled or modulated by allosteric effectors
    allosteric enzymes
  12. reason why enzymes are used as a clinical markers for certain disease
    bec. they are found in specific sites/ organelles within the cell
  13. decrease the rate of reaction
    lowering the ACTIVATION ENERGY
  14. initial input of energy
    activation energy
  15. gives alternate route, one with lower energy of activation
    catalyst
  16. place where substrate binds to enzyme
    enzyme active site
  17. formed due to folding and bending of the protein
    enzyme active site
  18. usually a "crevice like" location in the enzyme
    enzyme active site
  19. two groups of Active Site
    catalytic and binding sites
  20. where enzyme attaches
    cleft or pocket
  21. additional non protein molecule needed by some enzymes to help reaction
    cofactor
  22. tightly boung cofactor
    prosthetic group
  23. organic co factors that are bound and released easily are called ________
    coenzyme
  24. types of cofactor
    • coenzyme
    • metal ion
  25. protein part of an enzyme that is inactive. requires cofactor to be activated
    apoenzyme
  26. apoenzyme + cofactor →
    holoenzyme
  27. the complete catalytically active enzyme
    holoenzyme
  28. enzyme requiring metal ion as cofactor
    metalloenzyme
  29. transport substrates from port of generation to port of utilization
    coenzyme
  30. most common metal ion
    Co Cu Mg Mn Zn
  31. example of prosthetic group
    PP FAD TPP Biotin
  32. thiamin pryophosphate
    Thimamine/ B1
  33. FAD, FMN
    Riboflavin/ B2
  34. NAD+ and NADP+
    Nicotinic acid/ niacin/ B3
  35. PLP
    Pyridoxine/ B6
  36. coenzyme A
    Pantothenic acid/ B5
  37. Biotin
    Biocytin
  38. THF, tetrahydrofolate
    Folic acid
  39. deoxyadenoxyl cobalamine
    B12
  40. lipoate
    Lipoic acid
  41. substrate of an enzyme
    reactant
  42. 2 theories about active site
    • Lock & key hypothesis
    • Induced Fit theory
  43. fit betweeen the substrate and the active site of enzyme is exact
    Lock & key hypothesis
  44. specificity of Lock & key hypothesis
    absolute specificity
  45. specificity explained by induced fit hypothesis
    broad specificity
  46. some proteins can change their shape
    induced fit hypothesis
  47. SIX major classes of Enzymes
    • [OTHLIL]
    • Ocidoreductase
    • Transferase
    • Hydrolase
    • Lyase
    • Isomerase
    • Ligase
  48. example of oxidoreductse
    dehydrogenase, oxidase
  49. example of transferase
    kinase, amino transferase/trans aminase
  50. example of hydrolase
    esterase, glycosidase, peptidase, phosphatase, phospholopase
  51. example of lysase
    decarboxylase, synthase
  52. example of ligase
    synthatase, carboxylase
  53. example of isomerase
    epimerase, mutase
  54. catalyze oxidation-reduction reactions
    Oxidoreductase
  55. Lactate + NAD→ Pyruvate + NADH + H+
    Oxidoreductase
  56. Stearate + FAD → oleate + FADH2
    Oxidoreductase
  57. In, L-lactate+NAD+ ⇆ Pyruvate + NADH + H
    Which is the Oxidizing Agent (gain H)?
    NAD+ (reduced)
  58. catalyze group-transfer reactions, and many require the presence of co enzymes
    Transferase
  59. L-Alanine + α-Ketoglutarate ⇄ Pyruvate + L-glutamate
    Transferase
  60. Glucose + ATP → Glucose 6P + ADP
    Transferase
  61. Aspartate +α-Ketoglutarate ⇄ oxaloacetate + glutamate
    Transferase
  62. Fructose-1P + ATP → fructose1,6-diP
    Transferase
  63. a specialized class of transferase, with water serving as the acceptor of group transferred, catalyzes hydrolysis
    Hydrolase
  64. pyrophosphate + H2O → 2 Phosphate
    Hydrolase
  65. Triglyceride + H2O → fatty acid + glycerol
    Hydrolase
  66. Starch + H2O → α-D-glucose
    Hydrolase
  67. Acetylcholine ester → choline + acetate
    Hydrolase
  68. ala-val-cys-lys + H2O → ala + val + cys + lys
    Hydrolase
  69. catalyzes lysis of a substrate, generating a double bond; these are nonhydrolytic, nonoxidative, elimination reactions
    Lyases
  70. Pyruvate + H+ → acetaldehyde + CO2
    Lyase
  71. Acetyl CoA + Oxaloacetate → citrate
    Lyase
  72. Alanine → propanoic acid + NH2
    Lyase
  73. Fumarate + H2O → malate
    Lyase
  74. Deoxyribose + purine/pyrimidine + Pi → DNA
    Lyase
  75. Oxaloacetate → CO2+ Pyruvate
    Lyase
  76. catalyze structural change within a single molecule, because these reactions have only one substrate and one product they are among the simplest enzymatic reactions
    Isomerase
  77. L-alanine ⇆ D-alanine
    Isomerase
  78. D-ribulose-5-phosphate → D-xylulose-5-phosphate
    Isomerase
  79. Fructose 1P → Fructose 6P
    Isomerase
  80. Glyceraldehyde-3P → DHAP
    Isomerase
  81. glucose 6P → fructose 6P
    Isomerase
  82. catalyze ligation, or joining of two substrates, these reactions require the input of the chemical potential energy of a nucleoside triphosphate such as ATP
    Ligase
  83. L-glutamate + ATP + NH4→ L-glutamine + ADP + Pi
    Ligase
  84. Pyruvate + CO→ oxaloacetate + ADP + Pi
    Ligase
  85. Factors affecting the reaction rate
    • substrate concentration
    • pH
    • temperature
    • Enzyme concentration
    • Cofactors
    • inhibitors
  86. plot of rate vs. enzyme concentration
    straight line (direct relationship)
  87. plot of rate vs. temp
    bell shaped
  88. plot of rate vs. pH
    bell shaped
  89. plot of rate vs. substrate concentration
    hyperbolic
  90. In rate vs. substrate concentration, when all the enzyme molecules are occupied
    V= Vmax
  91. causes the bell shaped plot in rate vs pH
    changes in state of ionization of AA side chain
  92. causes the decrease of rate when the temperature is beyond the optimum (37°C)
    denaturation
  93. the slope in Michaelis-Menten Equation
  94. Plot of Michaelis-Menten Eq.
    hyperbolic
  95. the y-intercept in Michaelis-Menten Equation
  96. a rate equation that relates the velocity of the reaction to substrate concentration
    Michaelis-Menten Equation
  97. Km is inverse measure of affinity of enz to its
    substrate
  98. Kis equal to substrate concentration at
     Vmax
  99. if S is ≥ Km
    there will be reaction
  100. if S is < Km
    there will be NO reaction
  101. low Km is equals to
    high affinity
  102. if the reciprocal of the MM eq. is dine
    LineWeaver-Burk (Double Reciprocal plot)
  103. enzymes that do not follow MM kinetics
    Allosteric Enzyme
  104. Plot of Allosteric Enzyme
    sigmoidal
  105. Allosteric enzymes displays
    cooperative bonding
  106. a site where small molecules (effectors) bind and cause conformational change in the enzyme
    allosteric site
  107. any molecule that acts directly on an enzyme to lower its catalytic rate
    inhibitors
  108. two major types of inhibition
    • reversible inhibition
    • irreversible inhibition
  109. inhibitors bind tightly, often covalently to the enzyme, permanently inactivating it
    irreversible inhibition
  110. inhibitors of acetylcholine esterase
    DIFP
  111. inhibit COX (cyclooxygenase), blood thinner
    Aspirin
  112. inhibits transpeptidase, destroys the bacterial cell wall
    penincillin
  113. inhibitor has close structural similarities to the normal substrate and therefore competes with substrate for he active site
    competitive inhibition
  114. example of competitive inhibition
    • Statin
    • Malonate
    • Methotrexate
  115. Km=↑ Vmax= same
    Competitive inhibition
  116. binds w/ active site, structurally identical w/ [S]affinity is decreased
    Competitive
  117. In a competitive inhibition, if [S] is increased
    Inhibitor is removed
  118. Km ↑
    affinity decreas
  119. aticholesterol drug, inhibits HMG CoA reductase
    Statin
  120. inhibits the succinate dehydrogenase
    Malonate
  121. anti cancer, inhibits di hydroforate reductase
    Methotrexate
  122. Inhibitors binds at E or ES complex Binds to a site other than the active site inhibition cannot be reversed by increasing the substrate concentration
    Non competitive inhibition
  123. ↑ [S] has no effect in inhibition
    Non competitive inhibition
  124. Vmax=↓  Km=same
    NC inhibition
  125. Binds at a site other than the active site and binds only to the ES complex
    Uncompetitive inhibition
  126. Km ↓  Vmax ↓
    uncompetitive inhibition
  127. Regulation of Enz
    • [EACZI]
    • End product inhibition
    • Allosteric modification
    • Covalent modification
    • proteolytic cleavage
    • induction & repression of enzyme synthesis
    • compartmentation
  128. negative feedback, product control/ inhibit its own synthesis
    End product inhibition
  129. ⊕ effector ↑ activity
    ⊖ effector ↓ activity
    Allosteric control
  130. phosphorylation & dephosphorylation
    Covalent Modification
  131. synthesis of glycogen (de P)
    glycogenesis
  132. beakdown of glycogen (P)
    glycogenelysis
  133. glycogen synthathase-OH → glycogen synthathae-OP (ATP)
    phosphorylation
  134. glycogen synthathae-OP → glycogen synthathase-OH (H2O)
    dephosphorylation
  135. way of activationg zymogens
    proteolytic cleavage
  136. inactive form of enzyme
    zymogens
  137. Premature activation of digestive enzyme result in
    pancreatitis
  138. very slow synthesis of enzyme
    Genetic control
  139. ↑ synthesis of enzyme
    induced
  140. ↓ synthesis of enzyme
    repression
  141. different form of an enzyme found in different organelles or different tissues
    Isozyme
  142. first released during MI
    Creatine Kinase
  143. predominates in the heart
    Ior H4
  144. predominates in the liver
    Ior M4
  145. Non enzymatic Protein
    troponin
  146. Major diagnostic enzyme used for MI
    [MI-LCS]

    • Lactate-dehydrogenase (tetramer)
    • creatin kinase (dimer)
    • SGOT or AST
  147. Major diagnostic enzyme used for pancreatitis
    [P-AL]

    amylase and Lipase
  148. Major diagnostic enzyme used for carcinoma of the prostate
    phosphatase acid
  149. Major diagnostic enzyme used for liver disease
    Alanine aminotransferase (ALT, SGPT) glutamyltranspeptidase

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