MBC Lecture 10 Enzymes

Question 0

Describe the biological importance of enzymes

Answer 0

Structure
Enzymes
Signals (hormones)
Receptors
Molecular machines

Question 1

Describe the features of enzymes

Answer 1

Reduce activation energy of a reaction
Active site with amino acid residues
Don’t change the position of equilibrium

Question 2

What are three examples of how enzymes are important in medicine?

Answer 2

Drugs: Ralenza
Diagnosis and prognosis: Cardiovascular disease, monitor CK as a marker of heart attack
Diseases caused by under or over activity: Phenylketonuria

Question 3

Describe a disorder caused by enzyme inactivity

Answer 3

Phenylketonuria

There is a mutation in the phenylalanine hydroxylase enzyme

These individuals can’t break down phenylalanine
Severe mental retardation
Treatment: remove phenylalanine from the diet

Question 4

Describe how enzymes are important in diagnosis and prognosis of disease
Use an example to explain

Answer 4

Eg. Cardiovascular disease

This disease has elevated levels of CK, AST and LDH

By monitoring these enzymes, we can diagnose and monitor the disease

Question 5

Which enzymes are present in individuals with cardiovascular disease?

Answer 5

CK
AST
LDH

Question 6

Describe how enzymes are Important drug targets

Answer 6

Eg. Ralenza targets the neurominadase enzymes that help new influenza viruses break out of the host cell

Question 7

Describe how enzymes are important for industry

Give an example

Answer 7

Food chemistry, agriculture, chemical engineering

Cheese production relies on chymosin

Question 8

What is chymosin?

Answer 8

An enzyme that is vital for cheese production

Question 9

What is Michaelis Menten good for?

Answer 9

Determining Vmax and Km (the concentration of substrate at which the enzyme is working at half it’s maximum possible speed

Question 10

What is V0?

Answer 10

This is the initial rate of reaction

Question 11

Describe how we determine Vmax and Km

Answer 11

Determine the rate of reaction as soon as substrate is added to a set amount of protein
Repeat for many concentrations of substrate

Plot a graph of [S] vs. V0

Question 12

What is Lineweaver-Burk analysis?

Answer 12

This is taking the reciprocal of the M-M equation

It allows us to more clearly see the effect of inhibitors on enzyme activity

Question 13

Describe the Michaelis Menten equation

Answer 13

.

Question 14

What is the Lineweaver Burk equation?

Answer 14

.

Question 15

List the four types of inhibition

Answer 15

Irreversible
Reversible:
Competitive
Uncompetitive
Mixed

Question 16

Describe irreversible inhibition

Answer 16

The inhibitor covalently binds to the active site of the enzyme

Question 17

Describe competitive inhibition

Answer 17

An inhibitor binds to the active site of the enzyme

Question 18

Describe uncompetitive inhibition

Answer 18

An inhibitor binds to some other site on the enzyme after the substrate has bound.
The substrate is not catalysed, and can’t be ejected

Question 19

Described mixed inhibition

Answer 19

Theis is when the inhibitor can bind either before or after the substrate has bound to the active site

Question 20

Draw all of the different graphs

Answer 20

.

Question 21

In which enzyme is there a mutation in phenylketonuria

Answer 21

Phenylalanine hydroxylase

Question 22

Km increases
Vmax stays the same

Which type of inhibition?

Answer 22

Cmpetitive

Question 23

Km increases
Vmax decreases

Which type of inhibition?

Answer 23

Mixed

Question 24

Km decreases Vmax decreases Which type of inhibition?

Answer 24

Uncompetitive