Lec 1: Enzymology Flashcards
The speed to which a reaction is completed
Reaction rate
The 3 major factors that influence reaction rate
- Concentration
- Temperature
- Pressure
A chemical reaction generally will occur when ___
When two particle reactants hit each other and start a reaction
[ TRUE or FALSE ]
- Higher concentration = faster rate reaction
- Higher pressure = faster reaction rate
- Higher temperature = lower kinetic energy = slower particle movement
- TRUE
- TRUE
- FALSE
It is the amount of kinetic energy particles have
Temperature
It is a substance that speeds up the rate of reaction without being consumed.
Catalyst
What is Activation Energy?
It is the minimum energy required to initiate the reaction
How does the catalyst work?
The catalyst will increase the reaction rate by lowering the Activation Energy.
It facilitates the reaction by binding to the reactants allowing them to interact optimally and start the reaction.
Enzyme
[ TRUE or FALSE]
All of the reactions found in the human body are reversible
FALSE
• Most of the reactions found in the human body are reversible
Differentiate Non-reversible reaction from Reversible Reaction.
Non-reversible reaction
• reactants »» products
• CANNOT convert back to the reactants
Reversible reaction
• reactants »» products
products »» reactants
• forward and backward reaction occur simultaneously
The state where the forward rate of reaction will equal the reverse rate of reaction.
Equilibrium
3 factors that will influence the movement of EQUILIBRIUM
- Concentration
- Temperature
- Pressure
[ TRUE or FALSE ]
An enzyme is a protein
TRUE
Define Active Site of an enzyme.
The Active Site is the central region that accommodates the substrate and facilitates the formation of the product.
What is a Catalytic Site of an enzyme?
It is part of the Active Site where catalysis will occur.
- Apoenzyme
- Holoenzyme
- It is an incomplete & inactive enzyme that needs a non-protein component to be activated.
- • It is the activated Apoenzyme
• apoenzyme + cofactor
- The most common metal ions the enzyme systems need.
- The common coenzymes required by enzyme systems.
- • Calcium
• Zinc
• Magnesium
• Manganese - • NAD
• NADP
• Pyridoxal 5’-phosphate
• Coenzyme A
An inactive enzyme that will activate itself upon encounter with a certain environmental factor
Zymogen
They are variants of the same enzyme that catalyze the same
reaction in a similar manner but different in location, susceptibility to inactivation, and electrophoretic mobility.
Isoenzymes
LDH and their Primary Tissue location:
- LDH 1
- LDH 2
- LDH 3
- LDH 4
- LDH 5
- Heart
- RBC
- Brain, pancreas, kidney, spleen, lungs
- Placenta, kidney, pancreas
- Muscle, Liver
The 6 classifications of enzymes
- oxidoreductases
- transferases
- hydrolases
- lyases
- isomerases
- ligase
CLASSIFICATION OF ENZYMES
- It catalyzes oxidation/reduction (redox reaction)
- Like hydrolases, they can destroy bonds and remove functional groups, but they DO NOT incorporate water.
- It transfers a functional group from one substrate to another.
- It binds different materials together in order to create something else.
- It catalyzes hydrolysis or the breakdown of bonds by addition of water
- It will rearrange the structure of a substrate
- Oxidoreductases
- Lyases
- Transferase
- Ligase
- Hydrolase
- Isomerase
[ TRUE or FALSE ]
An enzyme that can act on only one specific substrate and corresponding reaction is called absolute specificity
TRUE
An enzyme that can act on all substrates that are of a certain structure of processing a particular functional group is called __.
Group specificity
Example of an enzyme with absolute specificity
Urease
Urease will ONLY act on urea, converting it to ammonia. If urea is modified, urease can’t act on it.
Example of an enzyme that is group specific
Hexokinase
It only acts on sugars that have 6 carbon atoms (mannose, fructose, glucose)
When the substrate enters the active site, the site does not perfectly fit the substrate’s shape at first. So the active site changes its structure to accommodate the substrate, optimizing the fit.
Induced Fit Model of Enzyme Action
- the speed of the reaction is dependent on substrate concentration
- the more substrates you have, the faster the reaction
First Order Kinetics
- the rate of the reaction is dependent on the enzyme concentration
- there is excess substrate but further addition of it will no longer have any effect
Zero Order Kinetics
Michaelis Menten Equation
Vo = Vmax [S]
Km + [S]
[ TRUE or FALSE ]
The Lineweaver Burk Plot is the linear graph of your Michaelis Menten
TRUE
How do pH & temperate influence enzymatic reactions?
- Optimum pH level = good shape of Active Site
- pH level changes = Active Site shape changes
- if pH level returns to optimum level, Active Site also returns to its shape. Only if the change was not extreme.
- the same with temperature
Differentiate Coenzyme and Prosthetic group.
Coenzyme
• organic
• temporarily attaches to enzyme
Prosthetic group
• permanently attaches to enzyme
Competitive Inhibition
The inhibitor binds to the active site first, so that the substrate cannot bind to the enzyme
Non-competitive Inhibition
The inhibitor binds to an allosteric site, so that the active site will be deformed and will not work properly. So, catalysis happens at a slower rate.
Uncompetitive Inhibition
The inhibitor needs a substrate that is already bound to the enzyme ,so that the inhibitor will work. Without a substrate, the uncompetitive inhibitor is useless.
- transformation of 1 umol of substrate to product per minute
- expressed in IU/L
International Unit
- transformation of 1 umol of substrate to product per second
- expressed in kat/L
Katal (kat)
What are the clinical reasons to analyze enzymes?
- to confirm a diagnosis
- to prognosticate
- to monitor treatment or progression of disease
Creatine kinase is responsible for the transfer of ___.
Transfer of phosphate from ATP to creatine to form creatine phosphate
This enzyme is responsible for the transfer of phosphate from ATP to creatine to form creatine phosphate
Creatine kinase
LDH is responsible for the ___ reaction involving the conversion of ___ or vice versa.
• redox
• lactate to pyruvate
This enzyme is responsible for the redox reaction involving the conversion of lactate to pyruvate or vice versa.
Lactate dehydrogenase (LDH)
In what areas are the following found, with the highest activities?
- CK-MM
- CK-BB
- CK-MB
CK-MM: skeletal muscles
CK-BB: brain
CK-MB: heart
CK-MB
- Begins to rise within ___ hours after an infarction.
- Peaks at ___ hours.
- Returns to normal within ___ hours.
- 4 hours
- 12 to 24 hours
- 48 to 72 hours
- Normally, which LDH isoenzyme is highest?
- What LDH isoenzyme significantly increases in myocardial infarction?
- LDH-2 is highest in normal people.
- LDH-1 significantly increases because it is mostly found in the heart.
LDH
- Begins to rise in ___ hours.
- Peaks at ___ hours
- May remain elevated for ___.
- 12 to 24 hours
- 48 to 72 hours
- Almost 2 weeks or 10 days
Preferred marker for myocardial infarction
Troponin
- Why is troponin a preferred marker for myocardial infarction?
- Troponin increases in ___ hours, and remains elevated for up to ___.
- Very specific to the heart & very sensitive
- increases in less than 4 hours, remains for up to 2 weeks
[ TRUE or FALSE ]
AST
A. It is found in highest concentrations in heart, liver, and skeletal muscle
B. It can elevate only in hepatic conditions
A. TRUE
B. FALSE
• It can elevate even in non-hepatic conditions
[ TRUE or FALSE ]
ALT
A. There is only a significant increase when you have hepatic cause.
B. It is considered more specific to hepatocellular disease
A. TRUE
B. TRUE
- What is the purpose of ALP?
- What is the purpose of GGT
- Hydrolysis of phosphate
- It transfers the gamma glutamine functional group to an amino acid to form glutathione
an enzyme belonging to hydrolysis that catalyzes the breakdown of starch and glycogen
Amylase
The primary sources of this enzyme are the parotid gland and the pancreas
Amylase
It is an enzyme specific only to the pancreas
Lipase
- found in the liver
- one of the most important enzyme systems in the body
- metabolism of drugs, hormones, and various chemicals
(CYP) Cytochrome P-450
