Module 1: Enzymology Flashcards
1
Q
These are proteins produced by living cells that hastens chemical reactions in organic matter
A
Enzymes
2
Q
Enzymes are measured in terms of _____ and not in terms of their absolute values
A
Activity
3
Q
Enzymes are _____ molecules and they are normally confined within cells unless increased membrane permeability _____ them to enter the blood
A
Large molecules; allows
4
Q
Enzymes appear in the serum after ______, _____, or ______
A
Cellular injury, degradation of cells or from storage areas
5
Q
(T/F)
Abnormal large amounts of enzymes in serum
are used clinically as evidence of organ damage
A
True
6
Q
T/F
Each enzyme catalyzes a single reaction or a limited number of chemical reactions, and it is specific for a substrate that it converts to a defined
product
A
true
7
Q
Factors affecting enzymatic reactions
A
Enzyme concentration
Substrate concentration
Cofactors
8
Q
The higher the enzyme concentration, the faster is the reaction, because more enzyme is present to bind with the substrate
A
Enzyme concentration
9
Q
With the amount of enzyme exceeding the amount of substrate, the reaction rate steadily increases as more substrate is added
A
Substrate concentration
10
Q
However, when the substrate concentration reaches a maximal value, higher concentration of substrate no longer result in increased rate of reaction (________)
A
Saturation kinetics
11
Q
Nonprotein entities that must bind to particular enzymes before a reaction occurs
A
Cofactors
12
Q
Is an organic compound (second substrate)
A
Coenzyme
13
Q
Coenzymes
(T/F)
Increasing its concentration will increase the
velocity of an enzymatic reaction
A
true
14
Q
It is essential to achieve absolute enzymatic activity
A
Coenzymes
15
Q
Examples of Coenzymes
A
NAD
NADP
16
Q
Are inorganic ions which alters the spatial configuration of the enzyme for proper substrate
binding
A
Activators
17
Q
Examples of Activators
A
Calcium
Zinc
Chloride
Magnesium
Potassium
18
Q
Are inorganic ions attached to a molecule
A
Metalloenzymes
19
Q
Examples of Metalloenzymes
A
Catalase
Cytochrome oxidase
20
Q
Enzymatic reactions may not progress if an inhibitor interferes with the reaction
A
Inhibitors
21
Q
Physically binds to the active site of an enzyme
A
Competitive inhibitors
22
Q
It does not compete with the substrate but look for areas other than the active site
A
Non-competitive inhibitors
23
Q
The inhibitor binds to the enzyme-substrate (ES) complex
A
Uncompetitive inhibitor
24
Q
These are enzymes (polypeptide chains) having the same catalytic reactions but slightly different molecular structures – various forms occur because of differences in the amino acid sequence of enzymes
A
Isoenzymes
25
Enzymes are active at ____, ____, and ____
25°C, 30°C, and 37°C
26
____ is the optimum temperature for enzymatic
activity
37°C
27
(T/F)
Increasing temperature usually increases the rate of
a chemical reaction by increasing the movement of
molecules
true
28
The rate of denaturation increases as the
temperature increases, and is usually significant at
____ to ____
40°C to 50°C
29
______ may result to inactivation of enzymes
60-65°C
30
means for every 10°C increase in temperature, there will be a two-fold increase in enzyme activity
Temperature Coefficient (Q10)
31
Hydrogem ion concentration/pH
Most physiologic reactions occur in the pH range of __ to __
7 to 8
32
(T/F)
Extreme pH level may denature an enzyme or influence its ionic state resulting in structural change or change in the charge of amino acid residue in the active site
true
33
render enzymes reversibly inactive
Low temperature (refrigeration/freezing)
34
tends to denature proteins and should be avoided
Repeated freezing and thawing
35
preservation for longer period of time (enzymes)
-20°C
36
ideal storage temperature for substrate and coenzymes
2° to 8°C
37
ideal for storage of LDH (LD4 and LD5)
Room temperature
38
Mostly increases enzyme concentration
Hemolysis
39
Decreases enzyme concentration
Lactescence or Milky Specimen
40
To standardize enzyme nomenclature, the _______ adapted a classification system in 1961, and revised the standards in 1972 and 1978
Enzyme Commission (EC)
41
Enzymes are classified according to their ________, indicating a substrate and class of reaction catalyzed, and are designated by individual identification numbers
Biochemical functions
42
The first digit, places the enzyme in its _______
classifications (six classifications)
43
The second and third digits, represents the _______ to which the enzyme is assigned
subclass
44
The final and fourth number/s, is a _______ that is specific to each enzyme in a subclass
serial number
45
E.C. 3.1.3.2
Acid Phosphatase
46
E.C. 3.1.3.1
Alkaline Phosphatase
47
E.C. 3.2.1.1
Amylase
48
E.C. 2.6.1.2
Alanine Aminotransferase
49
E.C. 2.6.1.1
Aspartate Aminotransferase
50
E.C. 4.1.2.13
Aldolase
51
E.C. 3.4.15.1
Angiotensin Converting Enzyme
52
E.C. 2.7.3.2
Creatine Kinase
53
E.C. 3.1.1.7
True/Acetyl Cholinesterase
54
E.C. 3.1.1.8
Pseudocholinesterase
55
E.C. 2.3.2.2
Gamma Glutamyl Transferase
56
E.C. 1.1.1.49
G-6-PD
57
E.C. 3.1.1.3
Lipase
58
E.C. 1.1.1.27
Lactic Dehydrogenase
59
E.C. 3.1.3.5
5’ Nucleotidase
60
Catalyze the removal or addition of electrons (redox reaction)
Oxidoreductases
61
Catalyze the transfer of a chemical group other than hydrogen from one substrate to another
Transferases
62
Catalyzes hydrolysis or splitting of a bond by the addition of water (hydrolytic reactions)
Hydrolases
63
Catalyze removal of groups from substrates without hydrolysis. The product contains double bonds
Lyases
64
Catalyzes the intramolecular arrangement of the substrate compound
Isomerases
65
Catalyze the joining of two substrate molecules, coupled with breaking of the pyrophosphate bond in ATP or similar compound
Ligases
66
is water-free cavity, where the
substrate interacts with particular charged amino acid residues; is a 3-dimensional protein structure
Active site
67
is a cavity other than the active site; may bind regulator molecules
Allosteric site
68
When bound tightly to the enzyme, the coenzyme is called a _______
prosthetic group
69
Apoenzyme (enzyme portion) and coenzyme forms a complete and active system known as _______
holoenzyme
70
Digestive enzymes in its inactive form originally secreted from the organ of production is called a ______ or ______
proenzyme or zymogen
71
Is based on the premise that the shape of the key (substrate) must fit into the lock (enzyme)
Emil Fisher's Theory / Lock and Key Theory
72
Is based on the substrate binding to the active site of the enzyme
Kochland's Theory / Induced Fit Theory
73
A chemical reaction may occur spontaneously if the free energy or available kinetic energy is higher for the substrate than the product
Enzyme kinetics
74
(T/F)
An enzyme combines with only one substrate and catalyzes only one reaction (absolute specificity)
true
75
the reaction rate depends only on enzyme concentration
Zero-order reaction
76
the reaction rate is directly proportional to substrate concentration
First-order reaction
77
the reactants are combined; the
reaction proceeds for a designated time; the
reaction is stopped and measurement is made
fixed-time
78
multiple measurements of changed in absorbance are made during the reaction; it is
preferred than fixed-time
Continuous monitoring/kinetic assay
79
1 micromole of substrate/minute
International Unit (IU or U)
80
1 mole of substrate/second
Katal Unit (KU)
81
The units used to report enzyme levels are _______
activity units
82
(T/F)
Most enzymes are measured by monitoring the rate of absorbance change (kinetic assay) at 340nm as NADH is reduced or consumed, and it allows direct reporting either by IU or KU
true
83
In nonkinetic assay, absorbance is made at ________
10-second intervals for 100 seconds
84
Is a nonspecific enzyme capable of reacting with many different substrates
alkaline phosphatase
85
other name of ALP
Alkaline Orthophosphoric Monoester Phosphohydrolase
86
Its functions to liberate inorganic phosphate from an organic phosphate ester with the concomitant production of an alcohol
ALP
87
In healthy sera, alkaline phosphatase (ALP) levels are derived from ____ and ____
liver
bone (osteoblasts)
88
__ or __ blood group increases intestinal ALP after consumption of a fatty meal
B or O
89
major tissue sources of ALP
liver, bone, placenta, and intestinal
90
RV for ALP
30-20 U/L
91
major isoenzymes of ALP
liver ALP, bone ALP, placental
ALP, and intestinal ALP
92
carcinoplacental ALP
regan ALP, nagao ALP
93
Is found in lung, breast, ovarian, and gynecological cancers; bone ALP co-migrator; most heat stable ALP (65°C for 30 minutes); inhibited by phenylalanine reagent
regan ALP
94
Found in adenocarcinoma of the pancreas and bile duct, pleural cancer; variant of regan ALP; inhibited by L-leucine and phenylalanine
nagao ALP
95
ELECTROPHORESIS
_____ and _____ ALPs are the most anodal isoenzymes
______ ALP is the least anodal
liver and bone
intestinal
96
(T/F)
High-resolution electrophoresis using polyacrylamide gel and isoelectric focusing are capable of resolving multiple bands of ALP
true
97
It is performed at 56°C for 10-15 minutes
heat fractionation/stability test
98
HF/Stability test
______ ALP is the most heat stable; _____ ALP is
the most heat labile
placental
bone
99
Decreasing order of ALP heat stability:
placental,
intestinal, liver, and bone
100
This method uses different concentrations of phenylalanine, synthetic urea, and levamisole solutions
chemical inhibition test
101
Placental and intestinal ALPs are inhibited by ________ and ______ inhibits bone ALP
phenylalanine reagent
3M urea
102
______ reagent inhibits liver and bone ALP
Levamisole
103
Is considered as the most specific method; IFCC recommended method
Bowers and McComb (Szasz Modification)
104
It is a continuous-monitoring technique which requires a pH environment of 10.15 and should be read at 405nm
Bowers and McComb
105
It catalyzes the same reaction by ALP, except that it is active at pH 5.0
acid phosphatase
106
other name of ACP
Acid Orthophosphoric Monoester Phosphohydrolase
107
tissue sources of ACP
prostate (major source), RBCs, platelets, liver, and bone
108
RV for ACP
Male = 2.5-11.7 U/L (Total ACP), 0-3.5 ng/mL (Prostatic ACP)
109
For detection of prostatic adenocarcinoma
ACP
110
It is also useful in forensic clinical chemistry, in the
investigation of rape cases – vaginal washings are examined for seminal fluid-ACP activity, which can persists for up to 4 days
ACP
111
Is involved in the transfer of an amino group between aspartate and 𝛼-keto acids with the formation of oxaloacetate and glutamate
Aspartate Aminotransferase (AST)
112
AST
the ________ is the predominant form in serum
cytoplasmic isoenzyme
113
major tissue sources of AST
cardiac tissue, liver, and skeletal muscle
114
other sources of AST
kidney, pancreas, and RBC
115
RV for AST
5-37 U/L
116
* pH 7.5; 340 nm
* It uses malate dehydrogenase (MD) and monitors
the change in absorbance at 340 nm
karmen method
117
It has enzymatic activity similar to AST
Alanine Aminotransferase (ALT)
118
It catalyzes the transfer of an amino group from alanine to 𝛼-ketoglutarate with the formation of glutamate and pyruvate
ALT
119
The highest concentration is in the liver; more liver-specific than AST
ALT
120
major tissue source of ALT
liver
121
other soruces of ALT
kidney, pancreas, RBC, heart,
skeletal muscle, and lungs
122
RV for ALT
6-37 U/L
123
Aminotransferases are present in ______, _____, _____, and ______
human plasma, bile, CSF, and saliva
124
Aminotransferases require ________ (vitamin B6) as coenzyme (prosthetic group)
pyridoxal phosphate
125
Using pH 7.5; reading at 340 nm
couple enzymatic reaction
126
Is an enzyme that catalyzes the interconversion of lactic and pyruvic acids
Lactate Dehydrogenase
127
Is a zinc-containing enzyme that is part of the glycolytic pathway and is found in virtually all cells in the body
lactate dehydrogenase
128
tissue sources of LDH
heart, RBCs, kidneys (LD-1 & LD-2); lungs, pancreas, spleen (LD-3); skeletal muscles, liver, intestine (LD-4 & LD-5)
129
RV for LDH
100-225 U/L (forward reaction), 80-280 U/L (reverse reaction)
130
* Reaction is at pH 8.8
* Is the most commonly used method because it produces a positive rate (NADH) and not affected by product inhibition
wacker method (forward/direct reaction)
131
* Reaction is at pH 7.2
● It is about 2x faster as the forward reaction
● It is the preferred method for dry slide technology
● It uses a less costly cofactor and it has a smaller
specimen volume requirement
wrobleuski la due (reverse/indirect reaction)
132
other methods for LDH
wrobleuski cabaud
berger broida
133
It catalyzes the transfer of a phosphate group between creatine phosphate and adenosine diphosphate
creatine kinase
134
other name for CK
ATP-CREATINE-N-PHOSPHOTRANSFERASE
135
* It is involved in the storage of high-energy creatine PO4 in the muscles
● It is a dimeric molecule with small molecular size, composed of a pair of two different monomers called M and B
● It is found in small amounts throughout the body, but it is found in high concentrations only in muscle and brain, although CK from brain virtually never crosses the blood-brain barrier to reach plasma
CK
136
major tissue sources of CK
brain tissue, smooth and skeletal muscle, and cardiac muscles
137
RV for CK
Male = 15-160 U/L, Female = 15-130 U/L, CK-MB = <6% of total CK
138
isoenzymes for CK
CK-BB (brain type), CK-MB (hybrid type), CK-MM (muscle type)
139
methods for CK
tanzer-gilbarg assay
oliver-rosalki
140
most commonly used method; faster reaction for CK
oliver-rosalki
141
Is an expression of the percentage of the total CK that is attributed to CK-MB. This is commonly to know possible release of CK-MB from noncardiac tissues when total CK is very high
CK relative index (CKI)
142
It catalyzes the breakdown of starch and glycogen – an important enzyme in the physiologic digestion of starch
amylase
143
It is the smallest enzyme in size (with a MW of 50,000 to 55,000 daltons) – normally filtered by the renal glomerulus and also appears in the urine
amylase
144
major tissue sources of amylase
acinar cells of the pancreas
and the salivary glands
145
other tissue sources of amylase
adipose tissue, fallopian
tubes, small intestine and skeletal muscles
146
RV for amylase
60-180 SU/dL (somogyi units) &
95-290 U/L
147
* It is the classic reference method expressed in Somogyi units
● It measures the amount of reducing sugars produced by the hydrolysis of starch by the usual glucose methods
saccharogenic
148
It measures amylase activity by following the decreases in substrate concentration (degradation of starch)
amyloclastic
149
It measures amylase activity by the increase in color intensity of the soluble dye-substrate solution produced in the reaction
chromogenic
150
It measures amylase activity by a continuous-monitoring technique
coupled-enzyme
151
Is an enzyme that hydrolyzes the ester linkages of fats to produce alcohol and fatty acid
lipase
152
Major tissue source: Pancreas
Reference value: 0-1.0 U/mL
lipase
153
hydrolysis of olive oil after incubation for 24 hours at 37°C and titration of fatty acids using NaOH
cherry crandal
154
Most commonly used method; does not use 50%
olive oil
peroxidase coupling
155
Is a phosphoric monoester hydrolase; predominantly secreted from the liver
5' nucleotidase
156
It catalyzes the transfer of glutamyl groups between peptides or amino acids through linkage at a gammy carboxyl group
GGT
157
It is secreted by the liver – it reflects synthetic function rather than hepatocyte injury
pseudocholinesterase
158
Is also known as “peptidyldipeptidase A” or “kininase il”; a hydrolase enzyme
angiotensin-converting enzyme
159
* Is a copper-carrying protein and also an enzyme
● Is a marker for Wilson’s disease (hepatolenticular
disease)
ceruloplasmin
160
Is a marker for hepatobiliary disease
ornithine carbamoyl transferase
161
It functions to maintain NADPH in the reduced form in the erythrocytes
G6PD
