Enzymes Flashcards
Abnormal large amount of enzymes in serum are used clinically as evidence of?
Organ damage
When bind tightly to the enzyme, the coenzyme is called
Prosthetic group
Water free cavity
Active site
Inactive enzyme precursor. Coagulation factors and digestive enzyme
Proenzyme or zymogen
Where the substrates bind and undergo a chemical reaction
Active site
Active substance formed by a combination of a coenzymes and an apoenzymes
Holoenzyme
Binds regulatory molecules
Allosteric site
Substance acted upon enzyme, specific for each enzyme
Substrates
Promote change in shape
Allosteric site
Specific biologic proteins that catalyze biochemical reactions without altering the equilibrium point of the reaction or being consumed or changed in composition
Enzymes
Represents the subclass to which the enzyme is assigned
Second and third digits
Serial number that is specific to each enzyme in a subclass
Final and fourth number
Helper molecules, nonprotein substance added in the enzyme substance complex to manifest the enzyme activity
Cofactors
Places the enzyme in its classification
First digit
Catalyze the hydrolysis of various bonds.
Splitting of a bond by addition of water
Hydrolases
Catalyze the interconversion of geometric, optical or positional isomers
Isomerase
Protein portion of enzyme, subject to denaturation, in enzyme losses activity
Apoenzyme
Physical binding of a substrate to the active site of an enzyme
ES complex
Catalyze an oxidation reduction reaction between two substrates
Oxidoreductase
Catalyze the joining of two substrate molecules, coupled with breaking of the pyrophosphate bond in adenosine triphosphate or a similar compound
Ligases
Enzymes combined with only one substrate and catalyzes only one reaction
Absolute specificity
They combine with all the substrates containing a particular chemical group
Group specificity
Reaction rate is directly proportional to substrate concentration
First order kinetics
Excess energy
The energy required to raise all molecules in 1mol of a compound at a certain temperature to the transition state at the peak of energy barrier
Activation energy
Specific to chemical bonds
Bond specificity
pH range wherein most physiologic reactions occur
7-8
Enzymes that predominantly combine with only one optical isomer of certain compound
Stereoisomeric specificity
Only a fixed number of substrates is converted to product per second
Zero order kinetics
Inactivation temperature of enzymes
60-65C
Nonprotein entities that must bind to particular enzymes before a reaction occurs
Cofactor
Optimal pH is controlled by means of appropriate
Buffer solution
Catalyze the transfer of a group other than hydrogen from one substrate to another
Transferase
Incubation temperature
+/-1C
For every 10C increase in temperature, there will be two fold increase in enzymatic activity
Temperature coefficient
Alter the spatial configuration of the enzyme for proper substrate binding, linking substrate to the enzyme or coenzyme
Activators
Binds an enzyme at a place other than the active site but instead prevent all enzymatic activity by binding to all allosteric site located elsewhere on the enzyme
Noncompetitive inhibitor
Catalyze the removal of groups from substrates without hydrolysis.
The product contains double bonds
Lyases
Second substrate
Coenzyme
Physically bind to the active site of an enzyme and compete with the substrate for the active site
Competitive inhibitor
Appear in the serum following cellular injury
Enzymes
Enzymes are measured in terms of?
Change in:
Substrate concentration
Product concentration
Coenzyme concentration
Results in permanent loss or enzymatic activity
Permanent binding
Results from a change in the shape of the active site when an inhibitor binds to an allosteric site
Allosteric inhibitor
Reaction rate depends only on enzyme concentration
Zero order kinetics
Enzymes are active at what temperatures?
25, 30, and 37C
Binds to the enzyme substrate complex. Does not yield products
Uncompetitive inhibitor
Theory wherein based on the shape of the key must fit into the lock
Lock and key theory
The reactants are combined, the reaction proceeds for designated time, the reaction stopped and a measurement of the amount of reaction that has occurred is made
Fixed time method
An increase in the concentration of substrate molecules will result to the increase in the likelihood of the active site that will be filled by the substrates instead of inhibitors
Reversible competition
An organic factor
Coenzyme
Based on the substrate binding to the active site of the enzyme.
Induced fit theory
Coenzyme frequently measured in the lab
NADH
Multiple measurements of the absorbance changed are made during the reaction
Continuous monitoring
Results when binding of an activator molecule to an allosteric site caused a change in the active site that makes it capable a binding a substrate
Excitory allosteric inhibitor
Enzyme concentration are always performed in?
Zero order kinetics
Similar enzymatic activity but differ in physical, biochemical and immunologic characteristics
Isoenzyme
Increasing its concentration will increase the velocity of an enzymatic reaction.
Essential for complete enzymatic activity
Coenzyme
The reaction is assumed to be linear over the reaction time
Fixed time method
As the enzyme binds to the substrate the shape of the active site conforms precisely to the shape of the substrate
Induced fit
Convenient method of an enzyme quantitation is measurement of its?
Catalytic activity
Optimum temperature of enzymatic activity
37C
More advantageous over fixed time method because the linearity of the reaction may be more adequately verified
Continuous monitoring
Acid phosphatase is seen in
Prostatic carcinoma
Alanine transferase is seen in
Hepatic disorder
Alkaline phosphatase is seen in
Hepatic disorder
Bone disorder
GGT in
Hepatic disorder
Lactate dehydrogenase
Myocardial infarction
Hepatic disorder
Hemolysis
Carcinoma
Amylase in
Acute pancreatitis
Lipase in
Acute pancreatitis
Trypsin in
Acute pancreatitis
Aspartate aminotransferase
Myocardial infarction
Hepatic disorder
Skeletal muscle disorder
Myocardial infarction increase in what enzyme?
AST
CK
LD
Hepatic disorder increase in
ALT ALP AST GGT LD
Chymotrypsin in
Chronic pancreatitis insufficiency
Skeletal muscle disorder increase in
AST
CK
Acute pancreatitis increase in
AMY
LPS
Trypsin
Chronic pancreatitis insufficiency increase in?
Chymotrypsin
Elastase 1
Generally associated with ATP regeneration in contractile or transport system
CK
CK major sources
Skeletal, muscle and brain tissue
Predominant function occurs in muscle cells, where it is involved in the storage of high energy creatine phosphate
CK
CK level is considered as sensitive indicator of?
Acute myocardial infarction
Duchenne type
CK is a dimeric molecule with small molecular size composed of pair of two different monomers called
M and B
This is known to increase CK <5x URL
Intramuscular injection
The dominant isoenzyme of CK found in brain, intestine and smooth muscle
CK-BB
Highest concentration of CK BB is seen in
CNS
GIT
Uterus during pregnancy
Useful tumor associated marker
CK BB
CK isoenzyme that Migrate fastest
CK BB
CK-1
Serves as buffer
Component of CK reagent
Imidazole
Creatine kinase in
Myocardial infarction
Skeletal muscle disorder
The only tissue from which CK MB enters the serum in significant quantities
Myocardium
Measures decrease in absorbance at 340nm with optimum pH oh 9. CK method
Tanser-Gilbarg assay
Forward or direct method
Potent inhibitor
Urate and cystein
For the detection of myocardial damage
CK MB
Elastase-1 in
Chronic pancreatitis insufficiency
Forward method is coupled with
Pyruvate kinase-LD-NADH system
CK is sensitive with?
Light and pH
CK MB begin to rise in? Peak? Normalize?
Rise:4-8 hrs
Peak:12-24hrs
Normalize:48-72hrs
Released after cell lysis interferes with CK assay particularly with hemolysis of >320mg/dL
Adenylate kinase
CK MB is not elevated in?
Angina
Not usually measurable when tissue damage occurs
CK BB
With this amount, CK MB is considered as the most sensitive indicator of myocardial damage
> 6% of total CK
Both abundantly present in cardiac and skeletal muscle
CK MM
Pyridoxal phosphate functions as coenzyme
AST
Most commonly performed
2-6x faster
Optimal pH of 6.8
CK method
Oliver rosalki
Reverse indirect method
EC code of CK
EC 2.7.3.2
Involved in the transfer of an amino group between aspartate and alpha keto acids with the formation of oxaloacetate and glutamate
AST
Major source of AST
Cardiac tissue
Liver
Skeletal muscle
AST is for the evaluation of
Myocardial infarction
Skeletal muscle involvement
Hepatocellular disorder
In AMI, AST begin to rise? Peak? Normalize?
Rise:6-8hrs
Peak:24hrs
Normalize:within 5 days
Routinely used method for AST.
pH 7.5; 340nm
Karmen method
Karmeyhod used this indicator reagent to monitor the change in absorbance
Malate dehydrogenase
Two enzyme fraction of AST
Cytoplasm and mitochondrial
Predominant AST isoenzyme occurring in serum
Cytoplasmic isoenzyme
EC code of LD
EC1.1.1.27
Enzyme that catalyzes the interconversion of lactic and pyruvic acid
LD
LD 1 contain high levels of?
RBC and cardiac tissue
EC code of AST
EC 2.6.1.1
Hydrogen transfer enzyme that uses the coenzyme NAD+
LD
Markedly increased in hepatic carcinoma and toxic hepatitis
LD5
Two different polypeptide chain in LD
H and M
In AMI, LD levels rise? Peak? Normalize?
Rise:12-24hrs
Peak:48-72hrs
Remain elevated for 10days
Major isoenzyme in the sera of healthy individuals
LD2
LD isoenzyme. More abundant in skeletal muscle
LD5
G6PD in
Drug induced hemolytic anemia
Alcohol dehydrogenase LD isoenzyme
LD6
LD6 is elevated in
Drug hepatotoxicity and obstructive jaundice
LD6 is present in patients with
Arteriosclerosis
LD1 prefers what method? How bout Ld5?
LD1-forward
LD5-reverse
Screening test for AMI.
Small heme protein found in skeletal and cardiac muscle
Myoglobin
Highest level of LD are seen in
Pernicious anemia
Hemolytic disorder
Reverse method is coupled with
Hexokinase-G6PD-NADP system
Substrate that the represent LD1 activity of total LD
Alpha hydroxybutyrate
Marker for angina and early detector for AMI
Myoglobin
Method in myoglobin:
Based on latex enhanced immuno turbidimetric method
Diazyme myoglobin assay
Method in LD.
pH7.2
2x faster as the forwad
Wroblenski La due
Reverse
Complex of three proteins that bind to the thin filaments of cardiac muscle
Troponins
Most important marker of cardiac injury
Troponin
Specific for heart muscle
Valuable tool in diagnosis of AMI
Binds the troponin complex to tropomyosin
Troponin T
TnI in AMI
Onset:3-6hrs
Peak:12-18hrs
Normalize:5-10days
Liver specific enzyme
ALT
EC code of ALT
EC2.6.1.2
Regulate the calcium dependent interaction of myosin head with actin filament during striated muscle contraction
Cardiac troponin
Responsible for transmitting calcium signal that triggers muscle contraction
Troponin
Troponin is gold standard in?
Acute coronary syndrome
Inhibits the binding of actin and myosin
Very sensitive indicator
Troponin I
Troponin T in AMI
Onset:3-4hrs
Peak:10-24hrs
Normalize:7days
Significant in the evaluation of hepatic disorders. Monitors the course of hepatitis treatment and effect of drug therapy
ALT
Nonspecific enzyme capable of reacting with many different substrates
Alkaline phosphatase
Alkaline phosphatase EC code
EC3.1.3.1
Functions to liberate inorganic phosphate form an organic phosphate ester with the concomitant production of an alcohol
Alkaline phosphatase
In normal sera, ALP was derived from?
Liver and bone
This blood group increases intestinal ALP after consumption of a fatty meal
B and O blood group
ALP require this ion as an activator
Mg2+
Isoenzyme of ALP that migrate fastest? Slowest?
Fastest-liver ALP
Slowest-intestinal ALP
Isoenzyme of ALP that is most heat stable? Heat Labile?
Stable-placental ALP
Labile-bone ALP
Total ALP increased, what is the isoenzyme that is most frequently elevated? Associated disease?
Liver ALP
Obstructive jaundice
Bone ALP increased in?
Pagets disease or osteitis deformans
ALP levels are significantly decrease in ?
Hypophosphatasia
Isoenzyme characterized by the ectopic production of an enzyme by malignant tissue
Regan isoenzyme
Detected in lung, breast, ovarian and gynecologic cancers
regan isoenzyme
Regan is co migrator of?
Bone ALP
Regan is inhibited by?
Phenylalanine
Useful in monitoring the effects of therapy because it disappear on successful treatment
Regan isoenzyme
Detected in adenocarcinoma of the pancreas and bile duct, pleural cancers
Nagao isoenzyme
Nagao is inhibited by?
Phenylalanine and L-leucin
Heat stability test of ALP is performed at?
56C for 10-15mins
Catalyze the transfer of glutamyl groups between peptides or amino acids through linkage at a gamma carboxyl group
GGT
GGT EC code
Ec2.3.2.1
Elevated among individuals undergoing warfarin, phenobarbital, and phenytoin therapy
GGT
Cholinesterase EC code
EC3.1.1.7
Cholinesterase is marker of?
Insecticide and pesticides poisoning
Used to monitor the effect of muscle relaxants after surgery
Cholinesterase
Useful in differentiating the source of an ALP level
GGT
GGT is elevated in
Biliary tract obstruction
GGT is a sensitive indicator of?
Alcoholism
Involved in:
Peptide and protein synthesis
Regulation of glutathione levels
Transport of amino acid across cell membrane
GGT
Index of parenchymal function
Cholinesterase
Added to the reverse method to inhibit AK
Adenosine monophosphate
In AMI: myoglobin onset? Peak? Normalize?
Onset:1-3hrs
Peak:5-12hrs
Normalize:18-30hrs
Zinc containing enzyme that is part of the glycolytic pathway and is found virtually all cells in the body
LD
Method in LD determination. Most commonly used
Produces positive rate NADH
Not affected by product inhibition
Wacker method
Forward method
Tissue sources of LD
LD1&2-heart, RBC, kidneys
LD3-lungs, pancreas, spleen
LD4&5-skeletal muscles, liver, intestines
Major isoenzyme in the sera of a healthy person
CK MM
Catalyzes the breakdown of starch and glycogen
Amylase
Addition of these substances will make assay more sensitive and specific for AP detection
Colipase and bile salts
Measures amylase activity by following the decreases in substrate in substance concentration. Degradation of starch
Amyloclastic
The most predominant pancreatic amylase isoenzyme in acute pancreatitis
P3
Condition when amylase combined with immunoglobulin to form a complex that is too large to be filtered by the glomerulus
Macroamylasemia
Measures the amount of reducing sugars produced by the hydrolysis of starch
Measures the appearance of product
Saccharogenic
Major tissue sources of amylase
Acinar cells of pancreas and salivary glands
Amylase EC code
EC3.2.1.1
Stages in prostatic carcinoma
A and B- malignant tumor
C- prostate in pelvic area
D-metastasized tumor
Measures disappearance of starch
Amyloclastic
Amylase requires these ions for activation
Calcium and chloride ions
Smallest enzyme. Normally filtered by the glomerulus and also appears in the urine
Amylase
Enzyme that hydrolyzes the ester linkages of fats to produce alcohol and fatty acids
Lipase
Measures amylase activity by the increase in color intensity of the soluble dye substrate solution produced in the reaction
Chromogenic
Method for lipase: used an olive oil as a substrate and measured the liberated fatty acids by titration after a 24hr incubation
Cherry crandall method
Amylase isoenzyme
S type-ptyalin
P type-amylopsin
Catalyzes the same reaction made by ALP except that is active at pH5.0
Acid phosphatase ACP
Specific substrate of choice for quantitative endpoint reaction in ACP
Thymolphthalein monophosphate
Amylase in acute pancreatitis
Onset:2-12hrs
Peak:24hrs
Normalize:3-5days
Inhibitor of prostatic ACP
L-tartrate
Lipase EC code
EC3.1.1.3
Newborn screening marker
G6PD
Earliest pancreatic marker
Amylase
Coupling of several enzyme systems to monitor amylase activity
Continuous monitoring
G6PD EC code
EC1.1.1.49
Confirmed AMI occured
LD1>LD2
CKMB >6%
ALP and GGT
Biliary tract obstruction
Useful serum markers for the diagnosis of AMI
Troponin I
Important in HMP
G6PD
ACP EC code
Ec3.1.3.2
Salivary amylase inhibitor
Wheat germ lectin
CKMB>6% and LD2>LD1
Myocardial damage, not necessarily AMI
Useful in the forensic clinical chemistry in the investigation of rape cases
ACP
Enzymes in bone disorders
ALP and ACP
Common chronic skeletal disease
Excessive resorption of bone by osteoclastic activity
Irregular pattern of bone deposition
Pagets disease
Increased osteoblastic activity
Vitamin D deficiency
Rickets-children
Osteomalacia-adult
Effect of PTH to calcium and phosphorus
Little osteoblastic activity
Hyperparathyroidism
In acute pancreatitis lipase:
Onset:6hrs
Peak:24hrs
Remain elevated:7days
Normalize:8-14days
Most specific pancreatic marker
Lipase
For the diagnosis of prostatic carcinoma
ACP
LD2
Variety of noncardiac disorders
Identify angina patients with high risk of having AMI
Troponin T
AST increased
Liver cell necrosis
Common bone tumor
Osteogenic sarcoma
Ratio of acute pancreatitis
7-15%
Renal clearance decreased
Low ratio of <2%
Macroamylasemia
