ENZYMOLOGY P1 Flashcards
ENZYME CONCENTRATION
higher the enzyme concentration, the
faster is the reaction, because more
enzyme is present to the substrate
SUBSTRATE CONCENTRATION
With the amount of enzyme exceeding the
amount of substrate, the reaction rate
steadily increases as more substrate is
added
• However, when the substrate
concentration reaches a maximal value,
higher concentration of substrate no
longer results in increased rate of reaction
Enzymes are active at
25°C, 30°C, 37°C
optimum temperature for
enzymatic activity
37°C
↑temp: __ reaction
↑reaction
Rate of denaturation _____ as
temperature increases
increases
Temperature that may result to inactivation of enzymes
60-65°C
Temperature Coefficient (Q10):
every 10°C increase in temp, there will be a 2x increase in enzyme activity
Most reactions occur in pH of
7-8
Extreme pH level may cause
Denaturation
Low temperatures (refrigeration/freezing)
cause enzyme to be
reversibly inactive
Repeated freezing and thawing
denaturation
ideal temp. for preservation of
enzymes
-20°C
ideal storage temp for substrates
and coenzymes
2-8°C
ideal for storage of LDH (LD4 and
LD5)
22°C
mostly increases enzyme concentration
Hemolysis
mostly decreases enzyme concentration
Lactescence or Milky spx.
Shape of substrate (key) must fit into
enzyme (lock)
EMIL FISHER’S LOCK AND KEY THEORY
Based on the substrate binding to the
active site of the enzyme
KOCHLAND’S INDUCED FIT THEORY
An enzyme combines with one substrate and catalyzes one reaction
ABSOLUTE SPECIFICITY
An enzyme combines with substrates
in a chemical group
GROUP SPECIFICITY
An enzyme reacting with chemical
bonds
BOND SPECIFICITY
The reaction rate depends only on
enzyme concentration
ZERO-ORDER REACTION
The reaction rate is directly
proportional to substrate
concentration
FIRST-ORDER REACTION
• The reactants are combined
• The reaction proceeds for a designated
time
• The reaction is stopped, and
measurement is made
FIXED-TIME
• Multiple measurements of change in
absorbance made during the reaction
• it is preferred than fixed-time
CONTINUOUS MONITORING/KINETIC ASSAY
ENZYMES ARE MEASURED IN TERMS OF
- Change in the substrate concentration
- Change in the product concentration
- Change in coenzyme concentration
CAUSES OF ELEVATED
PLASMA ENZYME LEVELS
- Impaired removal of enzyme from
plasma - Impaired permeability of cell membrane
- Increased in the number of cells or the
production of cells - Increased in normal cell turnover
- Decreased clearance of enzymes from the circulation
- Tissue necrosis and degeneration
specific biologic proteins that catalyze
biochemical reactions without altering the
equilibrium point of the reaction or being
consumed or changed in composition
ENZYMES
A cavity other than the active site
Allosteric site
Forms of an enzyme could be based on
physical properties such as
• Electrophoretic mobility
• Solubility, or
• Resistance to inactivation
Fraction of an enzyme
ISOENZYME
Necessary for enzyme activity
COFACTOR
Inorganic cofactors
ACTIVATOR
Organic cofactors
COENZYME
Coenzyme bound tightly to the enzyme
PROSTHETIC GROUP
Enzyme secreted from the organ of
production in a structurally inactive form
ZYMOGEN
Prevents an enzymatic reaction to occur
INHIBITOR
Physically binds to the active site of an
enzyme; reversible
COMPETITIVE INHIBITOR
Looks for areas other than the active site;
slows the rate of the reaction
NON-COMPETITIVE INHIBITOR
The inhibitor binds the enzyme-substrate
complex
UNCOMPETITIVE INHIBITOR
Assigned systematic name to each
enzyme
INTERNATIONAL UNION OF BIOCHEMISTRY
FIRST DIGIT
Enzyme Class
SECOND AND THIRD DIGIT
Enzyme Sub-Class, Sub-sub-class
FOURTH DIGIT
Serial number specific to an enzyme
Catalyze an enzyme-reduction reaction
between two substrates
OXIDOREDUCTASE
Catalyze the transfer of a group other than
the hydrogen from one substrate to
another
TRANSFERASE
Catalyze hydrolysis of various bonds
HYDROLASE
Catalyze removal of groups from
substrates without hydrolysis
LYASE
Catalyze the interconversion of
geometric, optical, or positional isomers
ISOMERASE
Catalyze the joining of two substrate
molecules, coupled with a breaking of the
pyrophosphate bond in ATP or similar
LIGASE
