Enzymes Flashcards
Majority of the chemical reactions in our body are catalyzed by proteins known as?
enzymes
____, which are large molecules that increase the rates of chemical reactions without themselves undergoing any change.
enzymes
Majority of the enzymes in our body are what type of proteins?
fibrous or globular
globular
____ are enzymes made of ribonucleic acids. They catalyze the self-cleavage of certain portions of their own molecules
Ribozymes
Like all catalysts, enzymes do not change the chemical what? They, rather, increase the what?
singilan time!!!
chemical equilibrium; reaction rate
enzymes do not change equi just rxn rates
Enzymes cause reactions to occur faster by lowering or adjusting the?
activation energy
Enzymes increase ____ by anywhere from 109 to 10</sup>20</sup> times
reaction rates
A characteristic of an enzyme wherein it is being choosy, to the point of being able to distinguish between the stereoisomers of the same molecule
specific
what enzyme catalyzes the hydrolysis of peptide bonds of proteins on the C-side of K & R?
Trypsin
what enzymes specifically catalyze the hydrolysis of only the last amino acid on a protein chain – the one on the C-terminal end?
Carboxypeptidases
What do you call the enzymes that catalyze the hydrolysis of any triglyceride, but still do not affect carbohydrates or proteins?
Lipases
What do you call the protein-splitting enzymes that are in the blood, ready to promote clotting?
Proteases
Identify the group of enzyme
catalyze oxidations and reductions
redox reactions or transfer of electrons
Oxidoreductases
EC1
Identify the group of enzyme
catalyze the transfer of a group of atoms, such as from one molecule to another
transfer of a group from one substrate to another
Transferases
EC2
Identify the group of enzyme
catalyze hydrolysis reactions
addition of water to break bonds
Hydrolases
EC3
Identify the group of enzyme
catalyze the addition of two groups to a double bond or the removal of two groups from adjacent atoms to create a double bond
addition of groups to double bonds or removal to form double bonds
Lyases
EC4
Identify the group of enzyme
catalyze isomerization reactions
convertion of substrate into its isomer
Isomerases
EC5
Identify the group of enzyme
catalyze the joining of two molecules
Joining 2 molecules with the hydrolysis of ATP
Ligases
EC6 or synthetases
Identify the group of enzyme
helping the protein move across the cell membrane
this is new btw
Translocase
what do you call the measure of how fast an enzyme is able to catalyze the reaction?
Enzyme activity
In an enzymatic reaction, what do you call the molecule being acted upon?
Substrate
What do you call nonprotein parts of enzymes necessary for catalytic function?
cofactors
what do you call organic molecules that act as cofactors?
Coenzymes
What do you call the 3-D cavity of the enzyms with specific chemical properties to accommodate the substrate?
Active site
What do you call the process that increases the action of an enzyme?
Activation
What do you call the process by which a compound binds to an enzyme and lowers its activity?
Inhibition
If we keep the concentration of the substrate constant and increase the concentration of enzyme, what will happen to the rxn rate?
increases or decreases
increases
increases linearly
True or False
If the enzyme concentrations double, will the rxn rate double as well?
Yes
bcoz molar concentration of enzyme is almost always much lower than that of substrate
If we increase the substrate concentration and keep enzyme concentration constant, what will happen to the rxn rate?
increases or decreases
increases
but reaches a point where rxn rate stays the same even if substrate conc is increased
The rxn rate does not increase when substrate conc is further increased at constant enzyme conc. Why?
Saturation curve = substrate conc up, enzyme conc constant
(at saturation) substrate molecules are bound to all active sites of an enzyme
Increasing the substrate concentration can no longer increase the rate because the excess substrate cannot find any active sites to which to bind
When temperature is increased in a catalyzed reaction, what will happen to rxn rate?
increases
What will happen to the rxn rate when you go beyond the optimal temperature and pH?
increases or decreases
decreases
After a small temperature increase above the optimum, the decreased rate could be increased again by doing what?
lowering the temperature
Arrhenius suggested that catalysts speed up reactions by combining with the substrate to form some kind of intermediate compound called?
enzyme-substrate complex
What do you call the limitation of an enzyme to catalyze specific reactions with specific substrates?
substrate specificity
Identify the enzyme-substrate complex
enzyme is a rigid 3-D body wherein active site has a restricted opening into which only one kind of substrate can fit
Lock-and-Key model
Identify the enzyme-substrate complex
size and shape of the active site change when substrate enters
comparison of changes occurring in the shape of the cavity upon substrate binding to the changes in the shape of a glove when a hand is inserted
Induced-fit model
What do you call a molecule that reduces the activity of an enzyme?
inhibitor
What do you call the activity-reductor of enzymes wherein they bind to enzymes and then never let go?
renders the enzyme less productive
irreversible inhibitor
What do you call the activity-reductors of enzymes that unbind to restore its activity to its initial level?
reversible inhibitors
Identify the type of reversible inhibitor
while bound to the active site of the enzyme, substrate cannot bind
competitive inhibitor
Identify the type of reversible inhibitor
binds not to the active site of the enzyme. its binding changes the shape of the enzyme, rendering it less efficient
noncompetitive inhibitor
True or False
When a competitive inhibitor is present, maximum rxn rate may take place if and only if substrate conc is increased
True
inhibitor will be displaced from the active site in accord with Le Chatelier’s principle
True or False
In the presence of a noncompetitive inhibitor, maximum rxn rate may take place if and only if substrate conc is increased
False
noncompetitive inhibitors cannot be displaced by substrates kasi hindi naman sa active sites naka-bind. Therefore, maximum rxn rate will be lower than it would be in the absence of an inhibitor
What do you call the enzyme regulation process in which formation of a product inhibits an earlier reaction in the sequence?
Feedback control
What do you call the inactive forms of enzymes wherein a polypeptide chain must be removed to make them active?
Proenzymes or Zymogens
trypsin & chymotrypsin (from -gen precursors); trypsin (from trypsinogen) catalyzes chymotrypsinogen to chymotripsin
What do you call the regulation that takes place by means of an event that occurs at a site other than the active site?
Allosterism
any enzyme regulated by this is called allosteric enzyme
If a molecule or a substance binds other than the active site, it may enhibit enzyme action wherein the process is called? when enzyme action is stimulated in this process, it is called?
negative modulation; positive modulation
the substance that binds to an allosteric enzyme is called a what?
regulator
what do you call the site wherein the substance of an allosteric enzyme binds to?
regulatory site
What do you call the enzymes that perform the same function but have different combinations of subunits (& diff quaternary structures)?
Isozymes or Isoenzymes
What do you call the enzyme derived from yeast?
Invertase
This enzyme splits sucrose to gluctose and fructose and classified as a hydrolase
Invertase
cleaves glycosidic bonds at a1 b2
What is used to monitor enzyme activity in the experiment?
may be colored red or yellow
3, 5-dinitrosalicylic acid (DNS)
when dinitrosalicylic acids reacts with sugars to form 3-amino-5-nitrosalicylic acid, what color will be shown?
Red
DNS does not react with sucrose
Red coloration in dinitrosalicylic acid means that enzyme is active, indicating that the concentration of gluc & fruc is?
high or low
high
higher [gluc] & [fruc] = higher invertase activity
What is the official name of Invertase?
B-fructofuranosidase
EC classification of Invertase (full)
EC 3.2.1.26
