INTRODUCTION TO ENZYMOLOGY Flashcards
ppt base
Study of enzymes
1. Activity of enzymes
2. Chemical reactions it catalyzes
3. Clinical use
enzymology
Increases the speed of reaction
Protein catalysts
AKA excess energy
Activation Energy
The molecule upon which an
enzyme acts
substrate
Specific biologic proteins that
catalyze biochemical reactions
enzymes
Often water-free cavity. Region of an enzyme where substrate molecules bind and undergo chemical reaction
active site
changing the shape of the
enzyme or confirmation
Allosteric Site
impairs activity of the enzyme
Allosteric inhibitor
enhances activity of the enzyme
Allosteric activator
Results when an enzyme is
subject to posttranslational
modification
Isoform
Isoform of enzymes. Enzyme existing in different forms within the same individual but the same action
Isoenzyme
Organic cofactor such as nicotinamide adenine dinucleotide
Coenzyme
Inorganic cofactor like chloride
ion, magnesium ion
Activator
Nonprotein molecule that may
be necessary for enzyme activity
Cofactor
coenzyme that is bound tightly to the enzyme
Prosthetic group
Ability of an enzyme to choose
exact substrate from a group of
similar chemical molecules
Enzyme Specificity
- Enzymes may recognize and catalyze
- A single substrate
- A group of similar substrates
- A particular type of blood
Enzyme Specificity
AKA Zymogen
Inactive form or precursor of
enzyme
proenzyme
Oxidation and reduction
Oxidoreductase
– removal of H ion
Oxidation
– accept H ion
Reduction
Addition of water to a bond resulting in bond breakage
Hydrolases
Transfer of functional groups other than hydrogen from one
substrate to another
Transferases
Catalyze the joining of two large molecules by forming a new chemical bond
Ligases
Proposal that enzyme catalysis is a two-step process that consists of an initial adsorption whereby the substrate combines with the enzyme to form a noncovalent enzymesubstrate (ES) complex, followed by a second step in which
the ES complex decomposes into product (P) and free enzyme (E).
Michaelis-Menten Theory
Catalyze removal of groups from substrates without hydrolysis; the product contains double bonds
Lyases
Specific action of an enzyme with a single substrate postulated first by Emil Fischer in 1894
Lock and Key Theory
Rearrange the functional groups within a molecule and catalyze the conversion of one isomer into another
Isomerase
Concentration of substrates when the reaction reaches half of Vmax
Km
Binding of a substrate or some other molecule to an enzyme
causes a change in the shape
of the enzyme resulting
enhancement or inhibition of
the enzyme’s activity
Induced Fit Theory
Maximum velocity or rate at which the enzyme catalyzed a reaction
Vmax
A double-reciprocal plot of the
Michaelis-Menten constant
which yields a straight line
Lineweaver-Burk Plot
Reaction rate is directly proportional to the concentration of one of the reactants
First-order reaction
temp for denaturation
40-50
Reaction rate is independent of concentration of the reactants; increasing the concentrations of reactants does not speed up the rate of reaction
Zero-order reaction
Reaction rate is directly proportional to the concentration of two reactants
Second-order reaction
The higher the enzyme level, the
faster the reaction will proceed
Enzyme Concentration
pH level of enzymatic reactions
7.0-8.0
amylase denatures at what temp
45
normal temp for er
37
assay temp
25,30, or 37
ck denatures at what temp
37
it is able to fit at the active site. when it is there, the substrate is unable to bind to the enzyme and the desired reaction does not occur.
competitive inhibition
bound to the regulatory site. the active site is thus changed, and the substrate can’t bind to the enzyme
noncompetitive inhibition
Enzymatic reaction of interest is paired with a second enzymatic
reaction which can be conveniently and easily measured
Coupled-Enzyme Assay
Reaction is stopped by denaturation using strong acid, strong base, detergent, heat, cold application, irreversible inhibitors, EDTA
Fixed-Time Method
often convenient as a reagent for coupled-enzyme assay when neither NAD nor NADH is a coenzyme for the reaction
NAD or NADH
Multiple measurements, usually of absorbance change, are made
during the reaction at specific time intervals usually every 30 secs of
60 secs, or continuously by continuous-recording
spectrophotometer
Continuous-Monitoring Method
Amount of enzyme that will catalyze the reaction of 1 micromole of substrate per minute under specified conditions
International Unit
Enzyme concentration
International Unit per Liter (IU/L)
Amount of enzyme that will catalyze the reaction of 1 mole of
substrate per second under specified conditions
Katal Unit (mole/s)
