Exp 3: Enzymes Flashcards
Identify the term:
biological catalysts that accelerate the rate of biochemical reactions
enzymes
Identify the mechanism:
how enzyme accelerates the reaction rate
by reducing free energy activation
( a factor of up to 10^20 over an uncatalyzed reaction)
T/F:
an enzyme is regenerated after the reaction
true
T/F:
an enzyme changes the equilibrium of the reaction
false;
does not change
Identify the term:
suffix to identify enzyme
Name+ase
Enumerate:
chemical nature of enzymes
- majority are proteins
- some are RNA: ribozymes
T/F:
enzymes function at MILDER reaction conditions
true
T/F:
enzymes are efficient in catalyzing LOWER reaction rate than a chemical catalyst
false;
higher
T/F:
enzymes have LOW reaction specificity
false;
greater reaction specificity
(some catalyze the reaction of only one stereoisomer; others catalyze a family of similar reactions)
Identify the term:
biomolecule acted upon by the enzyme
substrate
Identify the term:
specific region of the enzyme that creates a 3D surface complementary to the substrate
active site
Enumerate:
6 classes of enzymes
EC 1: oxidoreductases
EC 2: transferases
EC 3: hydrolases
EC 4:lyases
EC 5: isomerases
EC 6: ligases
Identify the enzyme class
(based on the type of reaction catalyzed):
1. redox reactions
2. transfer of electrons
(hydride ions or H atoms)
oxidoreductases
Identify the enzyme class
(based on the type of reaction catalyzed):
transfer of a group from one substrate (donor) to another (acceptor)
transferases
Identify the enzyme class
(based on the type of reaction catalyzed):
hydrolysis (addition of H2O) of C-C, C-O, C-N and bonds like phosphoanhydride
hydrolases
Identify the enzyme class
(based on the type of reaction catalyzed):
addition (other than H2O) of groups to double bonds or removal of groups to form double bonds
lyases
Identify the enzyme class
(based on the type of reaction catalyzed):
1. convert the substrate into its isomer
2. transfer of groups within molecules to form isomers
isomerases
Identify the enzyme class
(based on the type of reaction catalyzed):
joining 2 molecules with the hydrolysis of ATP
ligases
Enumerate:
subclasses of oxidoreductases
- oxidases
- oxygenase
- hydroxylase/ monooxygenase
- dehydrogenase
- reductase
Identify which subclass of oxidoreductases:
introduction of one oxygen atom from a molecule of O2
oxidases
Identify which subclass of oxidoreductases:
introduction of both atoms of the O2 into the substrate
oxygenase
Identify which subclass of oxidoreductases:
1 atom of O2 is introduced to the substrate and the other atom forms water
hydroxylase/ monooxygenase
Identify which subclass of oxidoreductases:
redox where electrons are removed from the substrate
dehydrogenase
Identify which subclass of oxidoreductases:
e- (with accompanying H+) are added to the substrate
reductase
Identify the enzyme class
(based on the type of reaction catalyzed):
cleavage of chemical bonds by the transfer of water
hydrolase
Enumerate:
classifications of isomerase
- epimerase
- isomerase
- mutase
Identify which type of isomerase:
ribulose 5-phosphate _________
epimerase
Identify which type of isomerase:
triose phosphate __________
isomerase
Identify which type of isomerase:
change in position of a substituent
mutase
Identify other term:
ligase
also known as synthetases
Identify:
new classification of enzyme
translocases (EC 7)
Identify the enzyme class
(based on the reaction catalyzed):
assists movement of another molecule across a cell membrane
translocases
Enumerate:
factors affecting enzyme activity
- pH
- temperature
- enzyme concentration [E]
- substrate concentration [S]
- inhibitor
- cofactor
Identify:
pH at which an enzyme exhibits maximum activity (achieves Vmax/ maximum reaction rate)
optimal pH
Identify the degree of change in pH:
alters the charge of acidic and basic amino acid residues found in active site
slight change in pH
Identify the degree of change in pH:
denatures enzyme irreversibly; loss of catalytic activity
extreme pH
(too acidic/ basic)
Identify:
temperature at which an enzyme exhibits maximum activity
optimal temperature
Enumerate:
what happens at ↓ temp
↓ KE = less molecular collisions = ↓ rxn rate
Enumerate:
what happens beyond optimum T
- disrupts 3° structure of enzyme
- substrate may not fit the active site
- impedes catalytic reaction
Identify:
how E conformation is altered (may be irreversible)
by change in temperature
Identify the enzyme:
yeast-derived enzyme
invertase
Identify:
official name of invertase
β-fructofuranosidase (EC 3.2.1.26)
Determine:
hydrolysis of invertase
hydrolyzes α1→β2 glycosidic bond in sucrose
Identify:
invertase’s enzyme class
hydrolase
(catalyzing hydrolysis of the terminal non-reducing β-fructofuranosidase residues)
Fill in the blanks:
Invertase splits sucrose to _________ and __________.
glucose
fructose
Identify the method:
used to monitor enzyme activity
dinitrosalicylic acid method
Identify:
principle involved in dinitrosalicylic acid method
3,5-dinitrosalicylic acid (DNS) reacts with reducing sugars to form 3-amino-5-nitrosalicylic acid (ANS)
T/F:
DNS reacts with sucrose (non-reducing sugar)
false;
does not react
Identify:
DNS color
new color formed
DNS: yellow
upon reaction: red
Identify:
red coloration indication
↑ red coloration = ↑ [glucose & fructose] = ↑ invertase activity
