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Biocheem > Lecture 20 > Flashcards

Lecture 20 Flashcards

1
Q

What energy does binding the transition state lower?

A

𝛥G‡

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2
Q

What do enzyme active sites bind better to?

A

The enzyme rather than the substrate

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3
Q

What creates the activation energy barrier?

A

The high energy state that is associated with the intermediate

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4
Q

What is Preferential Transition State Stabilization?

A

A term used to describe that enzyme active sites will prefer to bind to the transition state over the substrate

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5
Q

What does it mean if an enzyme is able to bind more strongly to the transition state relative to the substrate?

A

The greater the catalytic activity of the enzyme and the more favorable to reaction is going to be

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6
Q

What are substrate or transition state analogs?

A

Things that look like but are not quite the substrate for a particular enzyme

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7
Q

What are potent inhibitors of many enzymes?

A

Transition state analogs

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8
Q

What do transition state analogs bind to and with what affinity?

A

The enzyme with higher affinity compared to the substrate

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9
Q

What kind of curve is seen in a Reaction Velocity vs Concentration Substrate graph?

A

A hyperbolic curve

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10
Q

What is Vmax on a reaction velocity vs. concentration of substrate curve analogous to?

A

100% binding of a ligand binding protein

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11
Q

What is Vmax?

A

The maximum rate at which an enzyme can catalyze the conversion of substrate into products

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12
Q

What does the Plateau region on a reaction velocity vs concentration of substrate graph represent?

A

When all the active sites are occupied with substrate as part of the reaction that is being cata;yzed

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13
Q

What determines Vmax in a Reaction Velocity vs Concentration of Substrate curve?

A

The amount of enzyme present

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14
Q

What is the formula for Vmax in a Reaction Velocity vs Concentration of Substrate curve?

A

𝛥[Product]/𝛥time

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15
Q

What does Km (the Michaelis constant) represent?

A

The substrate concentration at which the reaction velocity is 50% of the Vmax

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16
Q

What is Km analogous to?

A

Kd in ligand binding

17
Q

What does a smaller value of Km meaning?

A

The more steeper the hyperbola, and the more rapidly we would see conversion of substrate into product

18
Q

What is V0 on a Reaction Velocity vs Concentration of Substrate curve?

A

The rate that we see product being formed when the enzyme and the substrate are initially mixed together

19
Q

When does V0 = 50% Vmax?

A

When [substrate] = Km

20
Q

What are the six mechanisms for regulation of enzyme activity?

A
  • Competitive inhibition
  • Allosteric
  • Reversible covalent modification
  • Ionic signals
  • Regulation gene expression
  • Changes in subcellular localization
21
Q

Which mechanisms for regulation of enzyme activity affect the intrinsic activity of an enzyme?

A
  • Competitive inhibition
  • Allostery
  • Reversible covalent modification
  • Ionic signals
22
Q

Which mechanisms for regulation of enzyme activity do not affect the intrinsic activity of an enzyme?

A
  • regulation of gene expression

* changes in subcellular localization

23
Q

How can allostery effect regulation of an enzyme?

A

Changing the shape of a protein that is involved in catalyzing the reaction to increase or decrease the activity of the enzyme

24
Q

What is reversible covalent modification?

A

Changing the tertiary structure of proteins in some fashion covalent

25
Q

How can ions affect the regulation of enzyme activity?

A

Ions can bind to proteins and change their tertiary structure making them either more or less active

26
Q

What are Competitive inhibitors?

A

Substances that bind reversibly and noncovalently in the active site, resemble the substrate or transition state but do not react

27
Q

What does a competitive inhibitor do by binding into the active site?

A

It prevents the substrate from binding

28
Q

How do competitive inhibitors affect the rate of a reaction?

A

The decrease the rate of a reaction

29
Q

How do competitive inhibitors affect Km?

A

They increase Km

30
Q

In which direction do competitive inhibitors shift the activity curve?

A

They shift it to the right

31
Q

How do competitive inhibitors affect Vmax?

A

The do not change Vman

32
Q

How are competitive inhibitors related to the substrate?

A

They are similar to the substrate in shape and size but differ chemically in such a way that they cannot react

33
Q

What makes better competitive inhibitors transition state analogs or substrate analogs?

A

Transition state analogs

34
Q

Why do transition state analogs make better competitive inhibitors?

A

Because transition states bind better to active sites

Biocheem (38 decks)

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