Enzymes Flashcards
What is fermentation
Transformation of RAW material such as starch, sugar, etc., into industrial mixtures such as liquors
Biotransformation
transformation of defined precursors to desired target product (environmental friendly processes to treat waste)
Pharmaceutical industry
Synthesis and modification of antibiotics
product: HF corn syrup
Enzyme: Glucose isomerase
Product: Lactose-Free Milk
Lactase
Product: Acrylamide
Enzyme: Nitrilase
Product: Cocoa butter
Enzyme: Lipase
Product: Ampicillin
Enzyme: Penicillin Amylase
Product: L-methionine; L-valine
Enzyme: Aminoacylase
Product: L-cartidine
Enzyme: dehydrate/hydroxylase
Product: L-dopa
Enzyme: beta-tyrosinate
Binding sites are
Specific and reversible
Reversible binding
Equilibrium between the free and bound ligand
What are Enzymes
Protein catalyst that increase the rate of reaction without being changed in the process
Rate
Velocity
Substrate is
Enzyme reactant
Recommended names for enzymes (3)
Short, most commonly used
Suffix -ase attached to substrate of reaction
OR to description of reaction performed
Systematic names of enzymes (3)
More complete, complex, used when an enzyme has to be identified without ambiguity
Oxidoreductase
Catalyze reactions where a molecule is being reduced and one being oxidized (oxidation-reduction reactions)
Transferases
Transfer Carbon, Nitrogen, Phosphate containing groups
Hydrolases
Catalyze a hydrolysis cleavage reaction
Adds water
Lyases
Cleavage of C-C, C-S, C-N bonds
Isomerases
Rearrangement of bonds within a single molecule
Ligases
Join together (ligate) two molecules together in an energy dependent process (DNA Ligase joints two DNA molecules) between S,C,N,O
Polymerases
Polymerization reactions such as SNA or RNA synthesis
Proteases
Break down proteins by hydrolyzing bonds between amino acids
Kinases
Addition of phosphate groups to molecules
ATPases
Hydrolyzes ATP
Synthases
Synthesize molecules in anabolic reaction by condensing two smaller molecules together (ATP SYNTHASE)
ACTIVE SITE increases what
Special pocket called the active site which increases specificity
ENZYME-SUBSTRATE COMPLEX
Substrates binds to the enzyme, forming the complex ES causing confirmations change in the enzyme that allows a catalysis … an EP is formed
EFFICIENCY (catalyzed vs uncatalyzed)
Reactions catalyzed by enzymes are 10^3-10^8 faster than uncatalyzed reactions
SPECIFICITY
Enzymes interact with 1 of few substrates and catalyze only one type of reaction
T or F
Holoenzymes do not need cofactors
False some do need cofactors
E+CE= ?
ACTIVE (HOLOENZYMES)
E -CF= ?
INACTIVE (APOENZYME)
T OR F
ENZYME ACTIVITY CAN BE REGULATED SO THAT THE RATE OF PRODUCTS RESPONDS TO CELLULAR NEEDS
TRUE
IT CAN INCREASE OR DECREASE THE ENZYME ACTIVITY
Enzymes are located where?
In specific organelles in cell
Compartmentalization
Some reactions are isolated from others avoiding competition for the substrate or enabling more favorable conditions
Transition state
After the active site binds to substrate and initiates the conversion to products by transition state.
Stabilizing transition state an enzyme can greatly increase the concentration of reactive intermediate that can be converted to product accelerating the reaction
How does an enzyme increase the concentration of an reactive intermediate?
Through transition state which is when the substrate is converted to a product by accelerating the reaction
Enzymology
Measurement of the appearance of products as a function of time
Leonor Michaelis-Maud equation (ENZYME VS SUBSTRATE CONCENTRATION)
Concentration of substrate is GREATER than the concentration of enzyme
Leonor Michaelis-Maud equation describes what
describes how the velocity of reaction varies with the substrate concentration
Leonor Michaelis-Maud equation TIME
Enzymatic reactions show a steady-state, ES complex does not change with time
The rate of formation of ES is equal to the rate of breakdown
Leonor Michaelis-Maud equation VELOCITY
Initial velocity of reaction is used to analyze enzymatic reactions
Vo= (Vmax [S])/ (Km + [S])
Initial velocity Michaelis
Vo= (Vmax [S])/ (Km + [S])
Michaelis constant equation
Km= (k1+k2)/ k1
Reflects the affinity of the enzyme for substrate
T OR F
Km is equal to the substrate concentration at which the reaction velocity is half
TRUE
Km= [S] THEN Vmax/2
T OR F
Km varies with the enzyme concentration
FALSE
IS WITH THE SUBSTRATE CONCENTRATION
ENZYME CONCENTRATION (MICHAELIS)
the rate of the reaction is DIRECTLY PROPORTIONAL to the enzyme concentration
Order of reaction: 1st order
If [S] is LOWER than Km then the velocity of reaction is Nearly proportional to the concentration of substrate
Order Zero
at high substrate concentration, VELOCITY of reaction is CONSTANT and EQUAL to Vmax
Rate of reaction is independent of substrate concentration
T OR F
The plot of initial reactions velocity against substrate concentration is hyperbolic
TRUE
T OR F
Allosteric enzymes show a sigmoidal curve
True, they do not show a Michaels kinetics
Lineweaver-Burke plot
1/Vo= (Km/ Vmax[S]) + 1/Vmax
Factors that affect reaction velocity
Substrate concentration
Temperature
pH
Inhibitors
How does [S] affect velocity of reaction
The rate of an enzyme/catalyzed reaction increases with the substrate concentration until a maximal velocity is reached… SATURATION
TEMPERATURE vs velocity
Velocity increases with temperature until a peak is reached.
Further elevation of temperature will result in decrease of velocity … DENATURATION
DENATURATION IS?
when the temperature elevation is too high that it causes the velocity of the reaction to decrease
The optical temp for most mammalian enzymes is
35-40 C
pH and velocity (3)
Extreme pH conditions can affect reaction velocity
It affects the ionization state of active site
Denatured enzymes
Inhibitors
Any substance that can diminish the velocity of an enzyme catalyzed reaction
Reversible inhibitors
Bind to enzyme through NON COVALENT bonds
Competitive inhibitors
Binds to the same site of substrate competing with it
T OR F
CONPETITIVE INHIBITORS REDUCE AFFINITY, DECREASE Km, Vmax is changed
FALSE
REDUCE AFFINITY, INCREASE KM AMD VMAX IS UNCHANGED
SATING DRUGS ARE AN EXAMPLE OF WHAT TYPE OF INHIBITOR?
COMPETITIVE, IT OCCUPIES THE ACTIVE SITE OF E HYDROXYMETHYLGLUTANYL COA REDUCTASE
The 1st step of cholesterol synthesis is inhibited by ?
Competitive inhibitor
Non competitive inhibitor
Binds at a different site than the substrate can also bind to free enzymes
T OR F
NON COMPETITIVE INHIBITORS INCREASE VMAX AND CHANGE KM
FALSE IT DECRESES VMAX AND KM IS UNCHANGED
Catalytic activity of enzymes depend on small molecules called
COFACTORS
Cofactors are
Non protein molecule that work as helpers for the enzyme
COENZYMES
Small organic molecules derived from vitamins and can be tightly or loosely bound to enzyme
When coenzymes are tightly bound they’re called
Prosthetic groups
Loosely bound coenzymes are
Co-substrates because they bind to and are released from enzymes like substrates
Inactive precursors are activated how
Activated by cleavage of one of the few peptide bonds
Zymogens
Inactive precursors
T OR F
PROTEOLYTIC ACTIVATION NEEDS ATP
FALSE
What is the zymogens and active site of the synthesis in stomach
Pepsinogen, pepsin
What is the zymogens and active site of the synthesis in pancreas (cc, tt, pc, pe)
Chymotrypsogen- chymotrypsin
Trypsinogen- trypsin
Procarboxypeptidase- carboxypeptidase
Protealatase- elatase
Proteolysis: blood clotting is mediated by
A cascade of PROTEOLYTIC activations that ensure a rapid and amplified response to trauma
Fibrous protein collagen
Major constituent of skin and bone, derived from procollagen a soluble precursor
Example Developmental processes in proteolysis
Metamorphosis
Apoptosis
Programmed cell death
Enzyme activity regulation
Mechanisms for regulating enzyme activities, effector, results noted in enzyme action and time required to see the effect
Allosteric activation
Active site becomes AVAILABLE to the substrate when regulatory molecules bind to a DIFFERENT site on enzyme
Allosteric deactivation
Active site becomes INACTIVE to the substrate when regulatory molecules binds to different site on enzyme
What happens when modifiers bind to the enzyme in a different site than the substrate
It changes the affinity of the enzyme substrate reaction or modifies the maximal catalytic activity of the enzyme
Homotropic effectors
When substrate serves as an effector
Heterotopic effector
Effector is different from substrate
T OR F
FEEDBACK INHIBITION IS AM EXAMPLE OR HOMOTROPOC EFFECTORS
FALSE IS AN EXAMPLE OF HETEROTOPIC EFFECTORS
Covalent modificators
Addition or removal of a phosphate group from a specific amino acid on the enzyme (ser, thru, tyr)
T OR F
CELLS CANNOT REGULATE THE AMOUNT OF ENZYME ALTERING THE RATE OF ENZYME DEGRADATION OR THE RATE OF SYNTHESIS
FALSE
THEY CAN
INCREASE= KNDUCTION
DECREASE=Repression
How can we use enzymes in clinical diagnosis
Through blood tests.
High plasma levels means
Damage
