MBC Lecture 10 Enzymes Flashcards
Describe the biological importance of enzymes
Structure Enzymes Signals (hormones) Receptors Molecular machines
Describe the features of enzymes
Reduce activation energy of a reaction
Active site with amino acid residues
Don’t change the position of equilibrium
What are three examples of how enzymes are important in medicine?
Drugs: Ralenza
Diagnosis and prognosis: Cardiovascular disease, monitor CK as a marker of heart attack
Diseases caused by under or over activity: Phenylketonuria
Describe a disorder caused by enzyme inactivity
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
Describe how enzymes are important in diagnosis and prognosis of disease
Use an example to explain
Eg. Cardiovascular disease
This disease has elevated levels of CK, AST and LDH
By monitoring these enzymes, we can diagnose and monitor the disease
Which enzymes are present in individuals with cardiovascular disease?
CK
AST
LDH
Describe how enzymes are Important drug targets
Eg. Ralenza targets the neurominadase enzymes that help new influenza viruses break out of the host cell
Describe how enzymes are important for industry
Give an example
Food chemistry, agriculture, chemical engineering
Cheese production relies on chymosin
What is chymosin?
An enzyme that is vital for cheese production
What is Michaelis Menten good for?
Determining Vmax and Km (the concentration of substrate at which the enzyme is working at half it’s maximum possible speed
What is V0?
This is the initial rate of reaction
Describe how we determine Vmax and Km
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
What is Lineweaver-Burk analysis?
This is taking the reciprocal of the M-M equation
It allows us to more clearly see the effect of inhibitors on enzyme activity
Describe the Michaelis Menten equation
.
What is the Lineweaver Burk equation?
.
List the four types of inhibition
Irreversible Reversible: Competitive Uncompetitive Mixed
Describe irreversible inhibition
The inhibitor covalently binds to the active site of the enzyme
Describe competitive inhibition
An inhibitor binds to the active site of the enzyme
Describe uncompetitive inhibition
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
Described mixed inhibition
Theis is when the inhibitor can bind either before or after the substrate has bound to the active site
Draw all of the different graphs
.
In which enzyme is there a mutation in phenylketonuria
Phenylalanine hydroxylase
Km increases
Vmax stays the same
Which type of inhibition?
Cmpetitive
Km increases
Vmax decreases
Which type of inhibition?
Mixed
Km decreases
Vmax decreases
Which type of inhibition?
Uncompetitive
