BCH 451 EXAM 2 QUESTIONS AND ANSWERS WITH COMPLETE
SOLUTIONS VERIFIED
What does an Allosteric Effector do?
Changes the conformation of an enzyme, from an "r" to an "s" state or vice versa.
Most allsoteric effectors are positive(activator) or negative(inhibitor) modulators?
negative(inhibitor)
What does a sigmoidal curve tell the reader?
The cooperative interaction between subunits.
What covalent modifications effect Lysine?
Lysine has the most modification options. These include:Acetylation, SUMOylation,
ubiquitination,biotinylation, and methylation
What are the three amino acids that can be phosphorylated?
Serine, Threonine, Tyrosine
What domains does Phosphofructokinase have? How do they interact?
A Kinase and a Phosphotase domain, which have negative feedback, so only one can
be functional at a time.
How does Acetylation function? What exclsuive Amino Acid does it affect?
It neutralizes Lysine's positive charges, and adds an acetyl group which opens up DNA
What does Glycosylation do to an Amino Acid? How does our body use these
products?
It adds a sugar molecule onto the AA, and proteins can be up to 50% sugar by mass.
Used as markers for immune system (don't attack me!).
,What A.A. does Ubiquitination bind to? What does it target?
Lysine, targets proteasomes
What A.A. does SUMOylation affect?
Lysine, unknown how it targets.
What are Catalytic Mechanisms?
The mechanisms of functional groups that aid in cleavage and formation of bonds.
General Acid-Base Catalysis function
give and take protons using WEAK acids and bases(not water) to stabilize
intermediates
Metal Ion Catalysis mechanism?
metal or side-chain ionic interactions
Specific Acid-Base catalysis functions via?
Using the H30+ or OH- ions in water to stabilize intermediates
What Amino Acids are found interacting in General Acid-Base catalysis?
Glutamate, Aspartate, Lysine, Arginine, Cysteine, Histidine, Serine, Threonine, Tyrosine
Covalent catalysis mechanism? What is required for this to function?
A transient covalent bond. A nucleophile on the enzyme.(can be an A.A., functional
group, or cofactor)
What is a protease?
An enzyme that breaks down proteins and peptides.
what kind of protease is chymotrypsin? What is in the catalytic triad?
Serine Protease, (Aspartate, Histidine, Serine)
Importance of Histidine in Chymotrypsin function?
, Acts as a general base and removes a proton from Serine
Importance of Serine in Chymotrypsin function?
Becomes a stronger nucleophile, interacts with substrate
Importance of Asparagine in Chymotrypsin function?
Stabalizes the Histidine H-bond, Increases the pkA of Histidine from 6 to over 12.
What is the mechanism of Chymotrypsin? How many phases are there? What are
their names?
Uses both covalent catalysis and general acid base interactions. Has two phases,
Acylation phase and Deacylation phase.
What is the acylation phase in chymotrypsin doing?
Forms a covalent acyl-enzyme intermediate coupled to the cleavage of a peptide bond
What is the Deacylation phase in chymotrypsin doing?
regenerates the free enzyme.
How can we prove the existence of acyl-enzyme intermediate if it is reverted after
the reaction?
Steady-state kinetics. Calculate the ratio between ES complex and E concentrations.
How do we measure steady state kinetics?
We use an artificial substrate that shows a color in its product form. A Stop-Flow device
uses precise measurements up to milllisecond accuracy to measure absrobance.
What does Burst Kinetics indicate?
Indicates a post-product formation reaction that is the rate limiting step.
Rate limiting step of chemotrypsin?
Hydrolysis of acyl-enzyme
SOLUTIONS VERIFIED
What does an Allosteric Effector do?
Changes the conformation of an enzyme, from an "r" to an "s" state or vice versa.
Most allsoteric effectors are positive(activator) or negative(inhibitor) modulators?
negative(inhibitor)
What does a sigmoidal curve tell the reader?
The cooperative interaction between subunits.
What covalent modifications effect Lysine?
Lysine has the most modification options. These include:Acetylation, SUMOylation,
ubiquitination,biotinylation, and methylation
What are the three amino acids that can be phosphorylated?
Serine, Threonine, Tyrosine
What domains does Phosphofructokinase have? How do they interact?
A Kinase and a Phosphotase domain, which have negative feedback, so only one can
be functional at a time.
How does Acetylation function? What exclsuive Amino Acid does it affect?
It neutralizes Lysine's positive charges, and adds an acetyl group which opens up DNA
What does Glycosylation do to an Amino Acid? How does our body use these
products?
It adds a sugar molecule onto the AA, and proteins can be up to 50% sugar by mass.
Used as markers for immune system (don't attack me!).
,What A.A. does Ubiquitination bind to? What does it target?
Lysine, targets proteasomes
What A.A. does SUMOylation affect?
Lysine, unknown how it targets.
What are Catalytic Mechanisms?
The mechanisms of functional groups that aid in cleavage and formation of bonds.
General Acid-Base Catalysis function
give and take protons using WEAK acids and bases(not water) to stabilize
intermediates
Metal Ion Catalysis mechanism?
metal or side-chain ionic interactions
Specific Acid-Base catalysis functions via?
Using the H30+ or OH- ions in water to stabilize intermediates
What Amino Acids are found interacting in General Acid-Base catalysis?
Glutamate, Aspartate, Lysine, Arginine, Cysteine, Histidine, Serine, Threonine, Tyrosine
Covalent catalysis mechanism? What is required for this to function?
A transient covalent bond. A nucleophile on the enzyme.(can be an A.A., functional
group, or cofactor)
What is a protease?
An enzyme that breaks down proteins and peptides.
what kind of protease is chymotrypsin? What is in the catalytic triad?
Serine Protease, (Aspartate, Histidine, Serine)
Importance of Histidine in Chymotrypsin function?
, Acts as a general base and removes a proton from Serine
Importance of Serine in Chymotrypsin function?
Becomes a stronger nucleophile, interacts with substrate
Importance of Asparagine in Chymotrypsin function?
Stabalizes the Histidine H-bond, Increases the pkA of Histidine from 6 to over 12.
What is the mechanism of Chymotrypsin? How many phases are there? What are
their names?
Uses both covalent catalysis and general acid base interactions. Has two phases,
Acylation phase and Deacylation phase.
What is the acylation phase in chymotrypsin doing?
Forms a covalent acyl-enzyme intermediate coupled to the cleavage of a peptide bond
What is the Deacylation phase in chymotrypsin doing?
regenerates the free enzyme.
How can we prove the existence of acyl-enzyme intermediate if it is reverted after
the reaction?
Steady-state kinetics. Calculate the ratio between ES complex and E concentrations.
How do we measure steady state kinetics?
We use an artificial substrate that shows a color in its product form. A Stop-Flow device
uses precise measurements up to milllisecond accuracy to measure absrobance.
What does Burst Kinetics indicate?
Indicates a post-product formation reaction that is the rate limiting step.
Rate limiting step of chemotrypsin?
Hydrolysis of acyl-enzyme
