BCH 403 - Exam 2 Questions with Correct Answers Latest 2025
What are the 3 serine proteases? - Answers chymotrypsin, trypsin, elastase
What is the specificity of chymotrypsin? - Answers Bulky R-groups, hydrophobic
(F, W, Y)
What is the specificity of trypsin? - Answers Positively charged R-groups
(K, R)
What is the specificity of Elastase? - Answers Small neutral R-groups
(A, S)
What is the specificity pocket? - Answers Where a protease will cut a polypeptide
What type of peptidase is Carboxypeptidase A? Where does it cleave a peptide? - Answers Exopeptidase
- cleaves a peptide at the C-terminal carboxylate of the substrate
What is the specificity of Carboxypeptidase A? - Answers Hydrophobic bulky side chains on the C-
terminal of a protein
What is the prosthetic group of Carboxypeptidase A? - Answers Zinc 2+
What type of catalyst is Triose Phosphate Isomerase? - Answers An Acid-Base catalyst
What is the catalytic triad? - Answers Serine-195
Histidine-57
Aspartate-102
What is Serines role in the catalytic triad? - Answers Serine is an essential nucleophile
What is Histidines role in the catalytic triad? - Answers Histidine is a general acid-base
What is Aspartate's role in the catalytic triad? - Answers Aspartate is electrostatic, it enhances the
nucleophilicity of Serine
What is a coenzyme? - Answers a nonprotein component usually derived from vitamins that often bind
to enzymes and help function in catalysis or group transfers
What is a prosthetic group? - Answers subset of coenzymes that are tightly bound and can be inorganic
Is Zinc 2+ in Carboxypeptidase A a prosthetic group or a coenzyme? - Answers Zinc is a prosthetic group
since it is tightly bound to Carboxypeptidase A and is inorganic
, What are vitamins? - Answers Compounds that our bodies can not synthesize but are necessary for
function
Vitamins can be converted in our bodies to be used as ____? - Answers Coenzymes
How do some coenzymes function in oxidation/reduction reactions? - Answers Some coenzymes can
function as bases and pick up hydrogens, as well as their associated electrons
What are the 3 complexes in PDH and what are they associated with? - Answers E1 - TPP
E2 - LA
E3 - FAD
What are the 6 steps of the PDH mechanism? (Acetyl CoA formation) - Answers 1. Pyruvate
decarboxylation
2. Reduction and Transacetylation
3. Repositioning of the acetyl group
4. Transthiolation
5. Re-oxidation of the lipoamide
6. Re-oxidation of FAD
What are the functions of the 3 subunits of the PDH complex? - Answers E1 and E2 convert pyruvate
into Acetyl-CoA
E3 specifically resets the coenzymes
What happens during decarboxylation in the PDH mechanism? - Answers TPP in E1 deprotonates and
the now negative carbon attacks the carbon in pyruvate this causes a cleavage event on pyruvate and
leaves a 2 carbon group attached to the TPP
What happens during the Reduction and Transacetylation step in the PDH mechanism? - Answers The
carbanion attacks the disulfide bond in lipoamide (LA) causing a cleavage event that regenerates TPP
and leaves the 2 carbon group bound to LA
What happens during the repositioning step in the PDH mechanism? - Answers The arms of LA
reposition the 2 carbon group in order to get in proper orientation for the next step
What happens during transthiolation step in the PDH mechanism? - Answers The free floating CoA
cleaves the acetyl off of the lipoamide forming the product Acetyl-CoA and leaves one of the LA arms
protonated - which needs to be in the disulfide bond state
What are the 3 serine proteases? - Answers chymotrypsin, trypsin, elastase
What is the specificity of chymotrypsin? - Answers Bulky R-groups, hydrophobic
(F, W, Y)
What is the specificity of trypsin? - Answers Positively charged R-groups
(K, R)
What is the specificity of Elastase? - Answers Small neutral R-groups
(A, S)
What is the specificity pocket? - Answers Where a protease will cut a polypeptide
What type of peptidase is Carboxypeptidase A? Where does it cleave a peptide? - Answers Exopeptidase
- cleaves a peptide at the C-terminal carboxylate of the substrate
What is the specificity of Carboxypeptidase A? - Answers Hydrophobic bulky side chains on the C-
terminal of a protein
What is the prosthetic group of Carboxypeptidase A? - Answers Zinc 2+
What type of catalyst is Triose Phosphate Isomerase? - Answers An Acid-Base catalyst
What is the catalytic triad? - Answers Serine-195
Histidine-57
Aspartate-102
What is Serines role in the catalytic triad? - Answers Serine is an essential nucleophile
What is Histidines role in the catalytic triad? - Answers Histidine is a general acid-base
What is Aspartate's role in the catalytic triad? - Answers Aspartate is electrostatic, it enhances the
nucleophilicity of Serine
What is a coenzyme? - Answers a nonprotein component usually derived from vitamins that often bind
to enzymes and help function in catalysis or group transfers
What is a prosthetic group? - Answers subset of coenzymes that are tightly bound and can be inorganic
Is Zinc 2+ in Carboxypeptidase A a prosthetic group or a coenzyme? - Answers Zinc is a prosthetic group
since it is tightly bound to Carboxypeptidase A and is inorganic
, What are vitamins? - Answers Compounds that our bodies can not synthesize but are necessary for
function
Vitamins can be converted in our bodies to be used as ____? - Answers Coenzymes
How do some coenzymes function in oxidation/reduction reactions? - Answers Some coenzymes can
function as bases and pick up hydrogens, as well as their associated electrons
What are the 3 complexes in PDH and what are they associated with? - Answers E1 - TPP
E2 - LA
E3 - FAD
What are the 6 steps of the PDH mechanism? (Acetyl CoA formation) - Answers 1. Pyruvate
decarboxylation
2. Reduction and Transacetylation
3. Repositioning of the acetyl group
4. Transthiolation
5. Re-oxidation of the lipoamide
6. Re-oxidation of FAD
What are the functions of the 3 subunits of the PDH complex? - Answers E1 and E2 convert pyruvate
into Acetyl-CoA
E3 specifically resets the coenzymes
What happens during decarboxylation in the PDH mechanism? - Answers TPP in E1 deprotonates and
the now negative carbon attacks the carbon in pyruvate this causes a cleavage event on pyruvate and
leaves a 2 carbon group attached to the TPP
What happens during the Reduction and Transacetylation step in the PDH mechanism? - Answers The
carbanion attacks the disulfide bond in lipoamide (LA) causing a cleavage event that regenerates TPP
and leaves the 2 carbon group bound to LA
What happens during the repositioning step in the PDH mechanism? - Answers The arms of LA
reposition the 2 carbon group in order to get in proper orientation for the next step
What happens during transthiolation step in the PDH mechanism? - Answers The free floating CoA
cleaves the acetyl off of the lipoamide forming the product Acetyl-CoA and leaves one of the LA arms
protonated - which needs to be in the disulfide bond state
