Introduction to Enzymes Flashcards
Biologic protein that catalyze biochemical reaction
Enzyme
Enzyme decreases or increases velocity in the reaction?
Increases
Enzyme only acts as ______; since it ______
participant; not consumed, nor change reaction
Majority of the enzymes are located ____
Intracellularly
Functions of Enzyme
- Hydration of Carbon Dioxide (respiration)
- Nerve Induction
- Muscle contraction (locomotion)
- Growth and Reproduction
- Energy storage and use
it is readily available in the presence of enzyme
Heat
Components of Enzyme
Active Site
Allosteric Site
binding site of substrate
Active site
binds regulatory/effector molecules
Allosteric Site
binding of active and substrate is
HIGHLY SPECIFIC
Substance that ACTED UPON enzymes
Substrate
Lactose metabolism is accelerated due to
Lactase
Nonprotein portion of enzyme
Cofactor
3 types of Cofactor
- Coenzyme
- Activator
- Isoenzyme
Acts as second substrate
Coenzyme
Coenzyme is ORGANIC OR INORGANIC cofactor?
Organic
Example of Coenzymes
NAD
Nonmetallic or Metallic cofactor
Activator
Non metallic Activator are
Bromide
Chloride
Metallic Activator are
MICZ
Magnesium
Iron
Calcium
Zinc
Cofactor that has same enzymatic activity but differs in PHYSICAL, BIOCHEMICAL, IMMUNOLOGIC characteristics
Isoenzyme
Example of Isoenzyme
CK Isoenzyme
CK-MM
CK-MB
CK-BB
Protein portion of enzyme
Apoenzyme
Susceptible for protein denaturation
Apoenzyme
Protein denaturation happens under what temp
56 deg cel.
Coenzyme + apoenzyme
Holoenzyme
coenzyme is tightly bound to the apoenzyme; coenzyme belongs to
Prosthetic group
Enzyme classification and name is based on
Enzyme Commission of IUB (International Union of Biochemistry)
Long name; Involves the:
Substrate
catalyzed reaction
Coenzyme
Systemic name
Usable name; commonly used
Recommended name/Trivial name
consist of four digits
Enzyme Commission Numerical Code
Enzyme Commission: First Digit
Enzyme Class
Enzyme Commission: Second Digit
Subclass
Enzyme Commission: Third Digit
Enzyme Sub Subclass
Enzyme Commission: Fourth Digit
Specific serial number of Enzyme
Enzyme Classes are the ff:
Oxidoreductase
Transferase
Hydrolase
Lyases
Isomerase
Ligases
Enzyme class that catalyzes the transfer of charged ions
Oxidoreductase
Redox reaction between 2 substrate
Oxidoreductase
Examples of Oxidoreductase enzyme:
Lactate Dehydrogenase (LDH)
Glucose Phosphate Dehydrogenase (G-6-PD)
Transfer of specific particular group other than hydrogen ion
Transferase
A- + B = A + B-
Oxidoreductase
A-X + B = A + B-X
Transferase
Transferase Enzymes are
Alanine Amino Transferase
Aspartate Amino Transferase
Gamma Glutamyl Transferase
Kinase (Creatine Kinase, Phosphokinase)
catalyze hydrolysis of various chemical bonds
Hydrolase
Hydrolase enzymes are
Amylase (glycosidic)
Lipase (Ester bond)
Phosphatase (monophosphoester bond)
- Acid Phosphatase
- Alkaline Phosphatase
catalyzes the removal of a particular chemical group from substrate w/o hydrolysis/water
Lyases
does lyases retain the double bond of an enzyme
Yes
A-B + H2O = A-OH + B-H
Hydrolysis
ATP –> cAMP + PPi
Lyases
Lyases enzymes are
Fructose biphosphate aldolase
catalyze interconversion of geometric, optical, and positional enzyme
Isomerase
A –> B
Isomerase
Isomerase enzymes are
Triphosphate isomerase
catalyze the joining of 2 substrate
Ligases
Example of Ligase enzyme
Glutathione synthetase
Ab + C = AC + b
Ligase
2 substrates joined together with
breaking of pyrophosphate bond in ATP
lower the activation energy needed by enzymes results to
fast chemical reaction
catalytic mechanism of enzyme
E + S = ES»_space;> E + P
Enzyme combined with only one substrate
Absolute specificity
Enzymes combined with all substrate of a particular chemical group
Group Specificity
Group Specificity example
Kinases (binds with phosphate group)
enzymes bind with the chemical bond
Bond specificity
Example of Bond specificity
Amylase (glycosidic)
Lipase (Ester)
Phosphatase (monophosphoester)
Enzymes bind with one specific optical isomer
Stereoisometric specificity
Factors that Influence Enzymatic Reactions
Substrate Concentration
Enzyme Concentration
Cofactor
Inhibitor
Storage
Hemolysis
Lactesence/Lipemic
Increase substrate concentration results to
Increase enzymatic reaction
Condition by which excessive increase of substrate no longer affects the enzymatic reaction
Saturation Kinetics
Measurement of Enzyme activity that uses an increasing amount of substrate concentration
First-Order Kinetics
Rate of Reaction is DIRECTLY PROPORTIONAL substrate concentration
First-Order Kinetics
Increasing substrate concentration is used in
First-Order Kinetics
FIXED number of substrates is converted to product
Zero Order Kinetics
Increased enzyme concentration
Faster chemical Reaction
TRUE / FALSE
All increased enzymes are clinically significant
false
Example of an enzyme that is normally increased
G-6-PD
Most physiologic reaction occurs @ what pH
7.0-8.0
Most physiologic reaction occurs @ what pH
7.0-8.0
Enzymes that can react with extremely low and high pH
Phosphatases
Acid Phosphatase pH
3-5
Alkaline Phosphatase pH
10
Plays a vital role in reaction
Temperature
enzyme is active at what temp
25, 30, 37 deg cel
room temperature
25 deg cel
optimum temperature for enzymatic activity
Body temperature (37 deg cel)
Denaturation starts at what temperature
40-50
Protein is denatured at what temp
56
Temperature by which enzyme is inactivated
60-65
Temperature coefficient/ Q10
for every 10 deg cel increase temperature = 2 fold increase in enzymatic activity
Enhances spacial configuration of the enzyme
Activator
3 kinds of Inhibitor
Competitive Inhibitor
Uncompetitive Inhibitor
Noncompetitive inhibitor
prevents substrate conversion to a product
Inhibitor
competes with substrate to the active site
Competitive inhibitor
Kind of inhibitor that binds with the allosteric site
Noncompetitive inhibitor
slow down or affect velocity of enzyme reaction; decreases substrate reaction
Competetive inhibitor
slow down or affect velocity of enzyme reaction; decreases substrate reaction
Competitive inhibitor
inhibitor that binds with Enzyme-Substrate Complex
Uncompetitive Inhibitor
Preferred temperature for storage that maintains the enzymatic activity for long period of time
-20 deg cel.
Substrate and Coenzyme temperature storage
2 - 8 deg. cel.
Temperature storage for LDH
Room temperature (25 deg cel)
Thawing of serum sample can be done ___
Once
Hemolysis can cause false INCREASED / DECREASED enzyme activity
INCREASED
RBC contains enzymes; hemolysis causes to release these enzymes causing false elevation of enzyme concentration
Lipemic, Lactescence, Milky specimen causes false INCREASED / DECREASE enzyme activity
Decrease
Increase product concentration
Decrease substrate concentration (substrate –> product)
Decrease in Coenzyme concentration (NADH)
- Coenzyme (second substrate, indicator)
- Commonly used in Oxidoreductase reaction
Redox Reaction happens in the presence of
Coenzyme
There is an INCREASED/DECREASED on altered coenzyme concentration during enzyme activity
Increased
Enzyme catalytic activity uses what substrate kinetics
Zero-order kinetics
Measurement of catalytic activity is done at what phase of reaction
LINEAR
General Method for Measuring Enzymatic activity
Fixed Time (2-point) Assay
Continuous Monitoring Assay / Kinetic Assay
mix reagents (substrate/coenzyme) and sample (enzymes)
incubate
measure
Fixed Time Assay
multiple measurement at specific time interval
Continuous Monitoring Assay
Commonly used interval
60 secs
Kinetic Assay uses what type of substrate kinetics
Zero-order kinetics
expression of the relationship between the velocity of the enzyme reaction and substrate concentration
Michaelis-Menten Equation
IU (EC) unit
1 substrate umol/min (umol/min)
SI unit
Katal (mol/sec)
measurement of enzymatic mass is used for
isoenzymes
Isoenzymes are measured through their
Electrophoretic migration
Theory that is based on binding of substrate (key) to the active site (lock)
Emil Fishers (Lock and Key theory)
Theory by which the configuration of the substrate would be manipulated so that it will fit to active site
Kochland’s Induced fit Theory