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Biochemistry > Enzymes > Flashcards

Enzymes Flashcards

1
Q

1.How many amino acids in lysozyme?

2.How much make the active site?

  1. Most frequently found amino acid at the active site is?
A
  1. 129
  2. 5:
    35
    52
    62
    63
    101
  3. Serine
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2
Q
  1. Why ethanol is used for treating methanol poisoning?
  2. Competitive inhibitor of succinic acid is? And for what?
A
  1. Structural similarity with methanol so compete with it for alcohol dehydrogenase enzyme
  2. Malonic acid for succinate dehydrogenase
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3
Q
  1. Antimetabolities are what type of inhibitors?
    Give examples of antivitamins?
A
  1. Competitive as the block the metabolic rxn
    Antivitamins:
    Sulfanilamide—as antibacterial
    Dicumarol     (inhibits vitamin K reductase)—-used as anticoagulant

Aminopterin used in treatment of cancers

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4
Q

What happens to Km (substrate affinity) and Vmax values in competitive & non-competitive inhibition & un-competitive??

A

Competitive
Km—– increased
Vmax—–unchanged

Non-Competitive
Km—– Unchanged
Vmax—–lowered

Unln-Competitive
Km—– decreased
Vmax—–decreased

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5
Q
  1. Heavy metals can non-competitively inhibit enzymes by?
  2. What happens if covalent bonds are formed?
  3. What is the most commonly used antidote for heavy metal poisoning?
  4. Example of Uncompetitive inhibition?
A
  1. Binding with cysteinyl sulfhydryl groups
  2. Covalent bonds of heavy metals with *carboxyl group” & histidine results in irreversible inhibition
  3. Dimercaprol with -SH groups
  4. inhibition of placental alkaline phosphate by phenylalanine
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6
Q
  1. Suicide inhibition is a type of?
  2. Name some suicide inhibitors and their enzymes they inhibit?
A
  1. Irreversible

2

Alluprinol (Alloxanthine) —- xanthine oxidase

5-Fluorouracil (Fluorodeoxyuridylate) —- thymidylate synthase

Aspirin —- cyclooxygenase

Penicillin—- transpeptidase

Zidovudine (AZT) —- reverse transcriptase

Sarin—- acetylcholinesterase

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7
Q

Name some irreversible inhibitors and enzymes they inhibit?

A
  1. Idoacetate —- papain & glyceraldehyde-6-phosphate

2.Diisopropylfluorophosphate (DFP) —- (serine containing enzymes) serine proteases & acetylcholinesterase

3.Methalion (organophosphorus isectiscide) ——acetylcholinesterase

4.Disulfiram (antabuse) —-aldehyde dehydrogenase

7.Penicillin antibiotics —- serine containing enzymes

6.Cyanide —- cytochrome oxidase (to iron)

8.Fluoride— enolase (removes manganese)

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8
Q
  1. What is used for the treatment of AIDS?
  2. Which inhibitor inhibits nucleotide synthesis?
  3. Enzyme cyclooxygenase of prostaglandin synthesis is inhibited by?
  4. What inhibits bacterial wall synthesis?
  5. What is used for the treatment of gout?
A
  1. Zidovudine (AZT)
  2. 5-fluorouracil or fluorodeoxyuridylate
  3. Aspirin
  4. Penicillin & Amoxicillin
  5. Allopurinol or Alloxanthine
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9
Q
  1. Electron transport chain is inhibited by?
  2. Glycolysis is inhibited by?
  3. Drug used for treatment of alcoholism?
  4. Which drug causes paralysis of vital body functions?
  5. ______ is a nerve gas?
A
  1. Cyandie
  2. Fluoride
  3. Disulfiram (Antabuse)
  4. Malathion (organophosphorus insecticide)
  5. Diisopropylfluorophosphate (DFP)
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10
Q
  1. What are some cholesterol lowering drugs? They inhibit?
  2. Drugs employed to block HIV replication?
  3. Hypertension is treated by which drugs?
A
  1. Statin drugs(lovastatin)
    —–inhibit enzyme HMG CoA reductase
  2. Tenofovir
    Emtricitabine
    —–inhibit enzyme viral reverse transcriptase
  3. Captopril
    Enalapril
    —–inhibit angiotensin converting enzyme
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11
Q
  1. Synthesis of prostaglandins is switched off by?
  2. Self destruction of COX is assisted by?
  3. How can prostaglandin levels be raised?
A
  1. A Suicide enzyme cyclooxygenase (COX) (inhibited by aspirin)
  2. 15-hydroxyprostaglandin dehydrogenase (15-HPD)
  3. By inhibiting 15-HPD by:
    Indomethacin
    Sulfasalazine
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12
Q
  1. Which class of enzymes doesnot exhibits stereoisomerism.
  2. Peptide bonds between Aromatic amino acids are cleaved by?
  3. Trypsin cleaves peptide bonds involving?
  4. Hexokinase acts on what compounds?
A
  1. Isomerases— bcz interconversion of isomers
  2. Chymotrypsin?
  3. Arginine & lysine
  4. Glucose, Fructose, Mannose, Glucosamine
    But
    NOT galactose!!!!
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13
Q
  1. Name A protein coenzyme?
A
  1. Thioredoxin coenzyme for ribonucleotide reductase
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14
Q

Give examples of 3 types of thermodynamic reactions of enzymes?

A
  1. Isothermic
    Glycogen phosphorylase
  2. Exothermic
    Urease
  3. Endothermic
    Glucokinase
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15
Q
  1. Give examples of 2 classes of allosteric enzymes?
  2. Most of allosteric enzymes are ______ in nature?
  3. Allosteric enzymes exist in which conformational states?
  4. Protein phosphorylation is done by?
    Dephosphorylation?
A

K class of allosteric enzyme
Phosphofructokinase

V class of allosteric enzyme
Acetyl coA carboxylase

  1. Oligomeric
  2. 2 states:
    T (Tense or taut)
    Inhibitors favour—–T

R (Relaxed)
Activators & substrates favour—–R

  1. Phosphorylation—–kinases
    Dephosphorylation—-phosphatases
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16
Q

1.How acetylcoA levels promote acetylation & deacetylation?

  1. Where does fatty acid synthesis & oxidation occurs?
A
  1. If acetylCoA
    High——acetylation
    Low—–deacetylation
  2. Synthesis —– cytosol
    Oxidation—–mitochondria
17
Q
  1. The enzyme used to synthesize glucose from non-carbohydrate sources?
  2. Half-lives of?
    LDH4
    LDH1
    Amylase
  3. Which types of enzyme has short half lives?
A
  1. Pyruvate carboxylase from pyruvate & amino acids
    (So pyruvate carboxylase is repressed by glucose if it is in excess)
  2. LDH4—— 5-6 days
    LDH1—– 8-12 hours
    Amylase—- 3-5 hours
  3. Rate limiting
    (Regulatory enzymes are rapidly degraded & synthesized)
18
Q
  1. What are isoenzymes?
  2. Are they tissue specific?
A
  1. Isoenzymes, also known as isozymes, are different forms of an enzyme that catalyze the same reaction but have slight differences in their structure or composition. These variations can arise from genetic differences or tissue-specific expression. It’s like having different versions of a superhero with similar powers but subtle differences in their abilities!
  2. Yes,

One example of isoenzymes is lactate dehydrogenase (LDH).
LDH exists in different forms, or isoenzymes, depending on the tissues in which it is found. For example, LDH-1 is primarily found in the heart, while LDH-5 is found in skeletal muscle. These different forms of LDH have slightly different structures but perform the same catalytic function.

19
Q
  1. The less commonly used and most commonly used units for enzyme activity?
  2. Name a non protein enzyme?
  3. Streptokinase is used for?
  4. Use of asparaginase?
  5. Recombinant enzymes can treat what type of diseases?
A
  1. Less commonly—- Katal
    More commonly— international units or enzyme unit

1 IU = 16.67 nkat

  1. Rhibozyme (group of RNA acting as enzyme)
  2. Clearing blood clots
    (Plasminogen—-plasmin which attack fibrin clots)
    Along with tissue plasminogen activator—- treatment of myocardial infarction
  3. Treatment of leukemias
    (It reduces asparagine in the plasma bcz Tumor cells are dependant on asparagine for replication
  4. Some lysosomal storage diseases
    •Gaucher disease (B-glucosidase)
    •Pompe disease (a-glucosidase)
    •Fabry disease (a-galactosidase A)
20
Q
  1. glucose can be estimated by?
    Result?
  2. What is commonly used for immobilization of enzymes?
A
  1. Glucose oxidase & peroxidase — immobilized & coated on strip of paper—- for the detection of glucose in urine
    Result
    Oxidized toluene blue color is formed (intensity —depends on conc. Of glucose)
  2. Beaded gels & cyanogen bromide activated sepharose
    To preserve enzymes
21
Q
  1. Plasma specific enzymes are synthesized in the?
  2. Which enzymes are secretory enzymes?
    And other plasm enzymes which are associated with metabolism are called?
  3. Which types of enzymes are imp for diagnosis & prognosis of disease?
A
  1. Liver … Then enter the circulation
    E.g ceruloplasmin
  2. Digestive enzymes of GIT
    Amylase
    Pepsin
    Trypsin
    Lipase

Other plasma enzymes–Constitutive enzymes

  1. Non-plasma specific enzymes
22
Q

Which diseases can be diagonized by The activities of
Amylase
Lactate dehydrogenase
Creatine kinase
y-Glutamyl transpeptidase

A

Amylase
Acute pancreatitis
Acute parotitis (mumps)
Obstruction of pancreatic duct

Lactate dehydrogenase (LDH)
Myocardial infarction
Infective hepatitis
Leukemia
Muscular dystrophy

Creatine kinase (CK)
Myocardial infarction (early detection)
Muscular dystrophy

y-Glutamyl transpeptidase (GGT)
Alcoholism
Infective hepatitis
Jaundice

23
Q

Which diseases can be diagonized by The activities of
Alkaline phosphatase
Acid phosphatase
Aspartate transaminase
Alanine transaminase

A

Alkaline phosphatase (ALP)
Bone & liver diseases
Rickets
Hyperparathyroidism
Carcinoma of bone
Obstructive jaundice

Acid phosphatase (ACP)
(Good tumor marker)
Cancers of prostrate gland

Aspartate transaminase (AST/SGOT)
Myocardial infarction
Liver disease

Alanine transaminase (ALT/SGPT)
Acute hepatitis
Jaundice
Cirrhosis of Liver

24
Q

Out of SGPT & SGOT which is more specific for the liver disease?

A

SGPT—–Liver diseases
SGOT—–Heart diseases
Bcz of cellular distribution

SGPT—– cytosomal
SGOT—– cytosol & mitochondria

25
Q
  1. LDH catalysis interconversion of?
  2. How many isoenzymes of LDH? Write subunit contribution?
  3. Distribution of isoenzymes?
  4. Km values for LDH1 & LDH5? What happens to pyruvate?
A
  1. Lactate & pyruvate
  2. 5:
    LDH1—–H4
    LDH2—–H3M
    LDH3—–H2M2
    LDH4—–HM3
    LDH5—–M4

LDH tetrameric (4 subunits)
H subunit (acidic)—heart
M subunit (basic)—skeletal muscle

  1. LDH1—– heart
    LDH3—–brain & kidney
    LDH5—-skeletal muscles
  2. LDH1—–high Km(low affinity for pyruvate)
    Pyruvate—–acetyl coA
    LDH5—–low Km(high affinity for pyruvate)
    Pyruvate—–lactate
26
Q
  1. What happens to LDH Levels in?
    Normal
    Myocardial infarction
    Liver disease?
  2. Where is LDH activity higher RBC or serum?
A

normally
LDH2 —-higher than LDH1

Myocardial infarction
LDH1 is greater than LDH2
(12-24 ours after infarction)

Liver diseases
LDH 5 —- elevated

  1. RBC (80-100 timez) higher
27
Q
  1. CPK (or CK) catalysis interconversion of?
  2. How many isoenzymes of CPK? Write subunit contribution?
    Distribution of isoenzymes?
  3. What happens to CPK levels in myocardial infarction?
A
  1. Phosphocreatine & creatine
  2. 3 isoenzymes:
    Dimer (2 subunits)
    CPK1—-BB—-Brain
    CPK2—-MB—-Heart
    CPK3—-MM—-skeletal muscle
  3. Normally
    CPK2—–2% In serum
    But In MI—– increases to 20%
    (CPK2 not elevated in skeletal disorders
    So CPK2 (MB) is early marker for MI)
28
Q
  1. How many isoenzymes of alkaline phosphatase?
    Which indicates hepatitis
    And which one bone diseases?
  2. How many iso enzymes of alcohol dehydrogenase
A
  1. 6 of ALP
    •a2-heat liable ALP—-hepatitis
    •Pre B-ALP—-bone diseases
  2. 2 heterodimer isoenzymes of ADH
    aB1— americans & europeans
    aB2—-japanese & chinese
    (More sensitive to alcohol)
    (aB2 Rapidly converts alcohol to acetaldehyde—– accumulate—-trachychardia)
29
Q

In diagnonosis through urine…
Which diseases can be diagonosed by increase in levels of following enzymes in urine?
Amylase
B-glucuronidase
B-N-Acetylgalactosidase

A

•Amylase—–acute pancreatitis
•B-glucuronidase—cancers of urinary bladder, pancreas
•B-N-Acetylgalactosidase—– renal graft dysfunction

30
Q

In diagnonosis through cerebrospinal fluid…
Which diseases can be diagonosed by increase in levels of lactate dehydrogenase in CSF?

A

LDH—– meningitis

31
Q

In diagnonosis through gastric juice…
Which diseases can be diagonosed by increase in activity levels of following enzymes in gastric juice?
B-glucoronidase?

A

B-glucoronidase—–gastric carcinoma

32
Q

1.Cystic fibrosis can be diagonized by?

  1. How type 1 glycogen storage disease can be diagnonized?
  2. In RBCs deficiency of the following enzymes cause?
    Glucose-6-phosphate dehydrogenase
    Transketolase
A
  1. Increased fecal trypsin levels
  2. Low glucose-6-phosphatase in
    Liver
  3. Glucose-6-phosphate dehydrogenase—-hemolytic anemia

Transketolase—-thiamine deficiency

33
Q
  1. McArdle’s disease can be diagonosed by?
  2. What is McArdle’s disease?
A
  1. Decreased phosphorylase activity in muscles
  2. McArdle’s disease, also known as glycogen storage disease type V, is a rare inherited disorder that affects muscle metabolism.
    People with McArdle’s disease have a deficiency of the enzyme called muscle glycogen phosphorylase, which leads to difficulty in breaking down glycogen into glucose for energy.
    This can result in muscle pain, fatigue, and cramps during exercise.
34
Q
  1. Enzymes in myocardial infarction diagnosis?
  2. Which is the 1st & last to be released?
  3. What are the non-enzymatic biomarkers of MI?
A

•. Creatine phosphokinase (CPK)
•. Aspartate transaminase (AST/SGOT)
•. Lactate dehydrogenase (LDH)

  1. First—-CPK
    Last—LDH
  2. • Cardiac troponins (troponin I & Troponin T)
    • myoglobin
    • high serum conc of Brain Natriuretic peptide (BNP) &
    Atrial Natriuretic Peptide (ANP)
35
Q
  1. Enzymes in liver disease?
  2. Enzymes raised in intra & extra hepatic cholestasis?
  3. Used for the diagnosis of alcoholic liver diseases?
  4. A marker for lung cancer, neuroblastoma (cancer in immature nerve cells), pheochromocytoma (tumor on adrenal gland)?
  5. Enzyme for detecting prostatic carcinoma?
A
  1. •Alanine transaminase
    •Aspartate transaminase
    •Lactate dehydrogenase
  2. •Alkaline phosphatase
    •5’nucleotidase
  3. y-glutamyl transpeptidase
  4. Neuron-specific enolase
  5. Acid phosphatase(tartarate labile)
36
Q
  1. Example of group specific enzyme?
  2. Example of bond specificity?
  3. Examples of broad specificity?
A
  1. Trypsin
  2. Glycosidases—-glycosidic bond of carbohydrates
    Lipases—-ester bonds of lipid
  3. Hexokinase
37
Q
  1. Examples of plasma-specific enzymes?
A

1.
Lipoprotein lipase
Plasmin
Thrombib
Choline esterase
Ceruloplasmin

Biochemistry (11 decks)

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