Enzymes Flashcards

1
Q

Biochemical activity of oxidoreductases

A

Catalyse oxidation/reduction reactions. Act on many chemical groups to add or remove hydrogen atoms

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2
Q

Example of an oxidoreductase

A

Lactate dehydrogenase

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3
Q

Biochemical activity of transferases

A

Transfer a functional group (amino or phosphate) between donor and acceptor molecules

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4
Q

Example of transferases

A
  • Transaminases (transfer of amino group NH2)
  • Phosphotransferases
  • Transmethylases, transpeptidases
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5
Q

Biochemical activity of hydrolases

A

Catalyse the cleavage of bonds by the addition of water across a bond

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6
Q

Examples of hydrolases

A
  • Protein hydrolysing enzymes - peptidases & proteases
  • Carbohydrases - amylase, maltase, lactase
  • Lipid hydrolysing enzymes - lipase
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7
Q

Biochemical activity of lyases

A

Cleave various bonds (C-C, C-S, C-N bonds) by means other than hydrolysis and oxidation

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8
Q

Examples of lyases

A
  • Aldose
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9
Q

Biochemical activity of isomerases

A

Catalyse inter conversion of optical, geometric or positional isomers within a single molecule.
Carry out many kinds of isomeriation:
* L to D isomerisation
* Mutase reactions (shifts of chemical groups)

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10
Q

Examples of isomerases

A
  • Isomerase
  • Mutase
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11
Q

Biochemical activity of ligases

A

Join two molecules with covalent bonds.
Catalyse rxns in which two chemical groups are joined (or ligated) with the use of energy from ATP

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12
Q

Examples of ligases

A
  • Glutamine synthetase
  • Acetyl-CoA carboxylase
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13
Q

Apoenzyme

A

Enzyme without its non protein moiety (cofactor) - inactive

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14
Q

Holoenzyme

A

Enzyme with its non protein component - active

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15
Q

What is the Michaelis-Menten Equation

A

V0=Vmax [S] / Km + [S]

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16
Q

Equation to determine Km

A

Km= (K-1 + K2) / K1

17
Q

What is Km

A

The substrate concentration at which the reaction velocity is half of the maximum velocity

18
Q

What does a small Km reflect

A

Small Km reflects a high affinity for substrate

19
Q

What does a large Km reflect

A

A large Km reflects a low enzyme affinity for substrate

20
Q

Y intercept on Lineweaver-Burk plot

A

1/Vmax

21
Q

X intercept on Lineweaver-Burk plot

A

-1/Km

22
Q

What does an allosteric inhibitor do

A

Binds to an enzyme someplace other than the active site

23
Q

What kind(s) of inhibition can be reversed by increasing [S]

A
  • Competitive inhibition