Enzymes

Question 1

What are intracellular enzymes?

Answer 1

Enzymes that are used in cells that produce them

Eg. Na-K ATPase

Question 2

What are extra cellular enzymes?

Answer 2

Enzymes which are Produced by cells in one place and secreted to other parts of the body
Eg. Digestive enzymes

Question 3

What are zymogens?

Answer 3

Secreted in an inactive form and activated by a diff. Enzyme
Eg. Pro thrombin ———————> thrombin
Thromboplastin

Question 4

What are zymase?

Answer 4

Enzymes secreted ready for action

Eg. Salivary amylase

Question 5

What are cofactors?

Answer 5

Additional non protein group required by some enzymes for its optimum activity
May be loose or tightly bound to protein part of enzyme

Coenzyme- org compounds
Activator- inorganic ions

Apoenzyme ( enzyme without cofactor) + cofactor –> holoenzyme ( complete catalytic ally active enzyme)

Question 6

Classification of enzymes

Answer 6

Oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases

Question 7

Explain and give examples of oxidoreductases

Answer 7

Catalyse oxidation reduction reactions
AH2 + B ———> A + BH2
Eg. Lactate dehydrogenase or cytochrome oxidase

Question 8

Explain and give examples of transferases

Answer 8

Catalyse the transfer of a group other than hydrogen ( eg. Amino, carboxyl) from one molecule to another

A-X + B —-> A + B-X

Eg. Aspartate transaminase, Alanine transaminase , hexokinase

Question 9

Explain and give examples of hydrolases

Answer 9

Catalyse cleavage of C-O, C-N, C-C bonds by adding water

AB+ H2O —> AH + BOH

Eg. Digestive enzyme - amylase, pepsin
Alkaline phosphatase

Question 10

Explain and give examples of lyases

Answer 10

Catalyse cleavage of C-O, C-N, C-C bonds by a mechanism other than hydrolyses

A-X
|. —–> A=B + X-Y
B-Y

Eg. Aldolase : fructose 1,6 bisphosphate —> G-3-P + DHAP

Fumarase

Question 11

Explain and give examples of isomerases

Answer 11

Catalyse intramolecular structural rearrangement

ABC—> CAB

Eg. Glucose-6-phosphate isomerase
Glucose-6-phosphate —> fructose-6-phosphate

Question 12

Explain and give examples of ligases

Answer 12

Catalyse joining of 2 molecules with simultaneous hydrolysis of ATP

A + B —> AB + [ADP+Pi]

Eg. DNA ligase

Question 13

How are enzymes clinically significant?

Answer 13

They are used for the disgnosis of disease
As therapeutic agents
As analytical reagents

Question 14

What are plasma specific enzymes?

Answer 14

Present in higher conc. in plasma than tissue
Eg. Blood coagulation enzymes
Ferroxidase

Question 15

What are plasma nonspecific enzymes?

Answer 15

High conc. in tissues

Released into blood during cell death/ disease

Question 16

Diagnostic importance of amylase

Answer 16

Acute pancreatitis

Question 17

Diagnostic importance of ALT

Answer 17

Liver diseases

Question 18

Diagnostic importance of AST

Answer 18

Myocardial infarction

Question 19

Diagnostic importance of alkaline phosphatase

Answer 19

Bone + liver diseases

Such as rickets/ obstructive jaundice

Question 20

Diagnostic importance of acid phosphatase

Answer 20

Prostate cancer as a tumour marker

Question 21

Diagnostic importance of Lactate dehydrogenase

Answer 21

Myocardial infarction

Question 22

Diagnostic importance of creatine kinase

Answer 22

Myocardial infarction

Question 23

Diagnostic importance of aldolase

Answer 23

Muscular dystrophy

Question 24

Diagnostic importance of 5’ nucleotidase

Answer 24

Hepatitis

Question 25

Diagnostic importance of gamma glutamyl transpeptidase

Answer 25

Alcoholism

Question 26

What is the therapeutic application ( enzyme used for treatment if disease) of streptokinase

Answer 26

To lyse blood clots

Question 27

What is the therapeutic application ( enzyme used for treatment if disease) of asparaginase

Answer 27

Treatment of some types of leukaemia

Question 28

What is the therapeutic application ( enzyme used for treatment if disease) of Papain

Answer 28

Anticoagulant

Question 29

What is the therapeutic application ( enzyme used for treatment if disease) of Alpha- anti trypsin

Answer 29

Treating emphysema

Question 30

What is the therapeutic application ( enzyme used for treatment if disease) of lysozyme

Answer 30

Treating eye infections | Found in tears and egg white

Question 31

What is the therapeutic application ( enzyme used for treatment if disease) of trypsin, pepsin, amylase, lipase

Answer 31

GIT disorders | Chronic pancreatitis

Question 32

What are the analytical application ( enzymes used as labels or reagents in analysis of a compound) of lipases

Answer 32

Triglycerols

Question 33

What are the analytical application ( enzymes used as labels or reagents in analysis of a compound) of cholesterol oxidase

Answer 33

Cholesterol

Question 34

What are the analytical application ( enzymes used as labels or reagents in analysis of a compound) of urease

Answer 34

Urea

Question 35

What are the analytical application ( enzymes used as labels or reagents in analysis of a compound) of glucose oxidase peroxidase

Answer 35

Glucose

Question 36

What are isoenzymes

Answer 36

Multiple forms of the same enzyme that catalyse the same biochemical reaction. They show different chemical + physical properties : electrophoretic mobility, kinetic properties Example: LDH & CK & alkaline phosphatase

Question 37

What is the normal value for CK

Answer 37

Males: 20-80 IU/L Females: 20-50 IU/L

Question 38

What are the 3 isoenzymes of CK

Answer 38

CK-1 : BB : tissue of origin- brain CK-2 : MB : tissue of origin- heart : myocardial infarction ( levels increase in 4 hours) CK-3 : MM : tissue of origin- skeletal muscle : muscular dystrophy

Question 39

What does lactate dehydrogenase catalyse and what are its isoenzymes

Answer 39

Oxidation of lactate to pyruvate LDH-1 : tissue of origin- heart, RBC LDH-2 : tissue of origin- heart, RBC LDH-3 : tissue of origin- brain, kidney LDH-4 : tissue of origin- liver, skeletal muscle LDH-5 : tissue of origin- liver, skeletal muscle LDH-1 : myocardial infarction LDH-2&3: leukaemia LDH2,3,4: tumour of testes+ ovary LDH-5 : liver disease

Question 40

What are the isoenzymes of ALP

Answer 40

Alpha-1 ALP : increased in obstructive jaundice Alpha-2 Heat stable ALP : increased in lung& colon cancer + pregnancy Alpha-2 heat labile ALP : increased in hepatitis Pre beta ALP : increased in bone disease Gamma ALP : increased in ulcerative colitis

Question 41

What are enzymes?

Answer 41

Important group of bio molecules produced by living cells Are soluble, colloidal, organic biological catalysts Protein in nature Specific in action Opt. Temp. In human body: 37 degrees Celsius

Question 42

What is specificity of enzyme action?

Answer 42

The ability of an enzyme to discriminate between 2 competing substrates Classified into: 1)Substrate specificity- absolute, relative & broad substrate specificity 2)Reaction specificity 3)Stereo specificity