33. EFFECTS OF LOCAL CONDITIONS ON ENZYME ACTIVITY Flashcards

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1
Q
  1. What kind of factors affect enzymes and why?
A
  • environmental factors
  • they are proteins
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2
Q
  1. What is Denaturtion?
A
  • the loss of a protein’s native conformation (shape)
  • this is due to unravelling
  • the protein loses its structure
  • the protein loses its function
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3
Q
  1. What are the three factors that affect Enzyme Activity?
A
  1. pH
  2. Temperature
  3. Cofactors
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4
Q
  1. What are Cofactors?
A
  • they are non-protein enzyme helpers
  • they are necessary for the function of enzymes
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5
Q
  1. What are the two types of Cofactors?
A
  1. Inorganic Cofactors
    • such as metal ions
    • metal ions are the cofactors for myelin and
      mitochondria reactions
  2. Coenzymes
    - these are organic factors
    - such as vitamins
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6
Q
  1. What effect does Temperature have on Enzyme Activity?
A
  • each enzyme has an optimal temperature
  • this is the temperature in which it can function
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7
Q
  1. What effect does pH have on Enzyme Activity?
A
  • each enzyme has an optimal pH
  • this is where it can function
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8
Q
  1. What are the two types of Enzyme Inhibitors?
A
  1. Irreversible Inhibitors
  2. Reversible Inhibitors
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9
Q
  1. What are Irreversible Inhibitors?
A
  • they bind to an enzyme
  • they bind via covalent bonding
  • this kind of inhibition is irreversible
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10
Q
  1. What are 3 general examples of irreversible Inhibitors?
A
  • several toxins
  • antibiotics
  • poisons
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11
Q
  1. What are three examples of irreversible inhibitors that inhibit nervous system enzymes?
A
  • Sarin
  • DDT
  • Parathion
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12
Q
  1. What do Penicillin Derivatives irreversibly inhibit?
A
  • they inhibit the enzyme transpeptidase
  • they synthesise the bacterial cell wall
  • this cell wall is called Peptidoglycan
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13
Q
  1. What are Reversible Inhibitors?
A
  • they bind to the enzymes
  • they bind using weak bonds
  • such as non-covalent bonds
  • this kind of inhibition is reversible

EXAMPLES OF NON-COVALENT INTERACTIONS:
- H- Bonds
- Hydrophobic Interactions
- Ionic Bonds

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14
Q
  1. What are the two types of Reversible Inhibitors?
A
  1. Competitive Inhibitors
  2. Non-Competitive Inhibitors
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15
Q
  1. What are Competitive Inhibitors?
A
  • these bind to the active site of an enzyme
  • they have weak binding
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16
Q
  1. What do Competitive Inhibitors compete with?
A
  • the substrate for the active site
  • they inhibit substrate binding to the active site
17
Q
  1. What happens during Normal Binding?
A
  • the substrate can bind normally to the active site of an enzyme
18
Q
  1. What happens during Competitive Binding?
A
  • a competitive binder mimics the substrate
  • it competes for an active site
  • this inhibits the substrate from binding
19
Q
  1. How can Inhibition (Competitive) be overcome?
A
  • excess substrate can be added
20
Q
  1. What are Non-Competitive Inhibitors?
A
  • they are inhibitors that bind to another part of an
    enzyme
  • they do not bind to the active site
21
Q
  1. What does the binding of Non-Competitive Inhibitors lead to?
A
  • a change in the shape of the enzyme
    (a loss in the function of the enzyme)
  • it can inhibit the function of the enzyme
22
Q
  1. Can Non Competitive Inhibition be overcome?
A
  • no
  • it cannot be overcome by adding extra substrate
23
Q
  1. What are the two characteristics that a cell’s Metabolic Pathways always have to have?
A
  1. must be tightly regulated
  2. pathways should only be activated when necessary
  • this is achieved by the regulation of the enzyme
    function
24
Q
  1. What are the two basic methods of Enzyme Regulation?
A
  1. Regulation of the enzyme production
    • by regulation of gene expression
  2. Regulation of enzyme activity
    • by feedback inhibition
      (allosteric regulation)
25
Q
  1. What is Feedback Inhibition?
A
  • it is the end product of a metabolic pathway
  • it inhibits the pathway
26
Q
  1. What is the role of Feedback Inhibition?
A
  • it prevents the cell from wasting chemical resources
  • it does this by synthesising more product than is
    needed
27
Q
  1. What are two examples of Feedback Inhibition?
A
  1. INHIBITION OF CATABOLIC PATHWAYS
    - this is done by ATP
    - the ATP is the end product
  2. INHIBITION OF ANABOLIC PATHWAYS
    • this is done by their end product
    • EG: Tryptophan synthesis pathways are inhibited by
      Tryptophan
28
Q
  1. What is Allosteric Regulation?
A
  • this is a form of reverse modulation
  • MODULATION = adjust, or change
  • it is common in enzymes
  • these enzymes have quaternised structures
  • it is also common in proteins
  • that have Polypeptide subunits
29
Q
  1. What kinds of Allosteric Regulation are there?
A

POSITIVE:
- this is known as Activation

NEGATIVE:
- this is known as Inhibition

30
Q
  1. What is a proteins’s function/activity at the active site affected by?
A
  • the binding of a regulatory molecule
  • this regulatory is usually at another site
    (regulatory site)
  • this is not always the case though
31
Q
  1. What do Regulatory Molecules bind to?
A
  • regulatory sites
  • they do this via non-covalent binding interactions
  • this is very similar to reversible non-competitive
    inhibitors
32
Q
  1. When do Enzymes change shape?
A
  • they change shape when the regulatory molecules bind
    to specific sites
  • this affects their function
33
Q
  1. What are the two types of molecular site bonding?
A

HETEROTROPIC:
- the regulatory molecules bind to sites other than the
active sites

HOMOTROPIC
- the regulatory molecule is the substrate
- it binds to the active sites

34
Q
  1. What do Allosteric Activators stabilise?
A
  • the active form of the enzyme
35
Q
  1. What do Allosteric Inhibitors stabilise?
A
  • the inactive form of the enzyme