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Biochemistry > Enzymes Of Clinical Practice/ Regulation Of Enzyme Activity > Flashcards

Enzymes Of Clinical Practice/ Regulation Of Enzyme Activity Flashcards

1
Q

The define isoenzymes

A

They have the same catalytic activity as an enzyme but different physical form.

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2
Q

What physical differences differentiate isoenzymes?

A

1) charge
2) AA sequence
3) molecular weight
4) electrophoric mobility
5) liability to inhibitor

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3
Q

4 isoenzyme examples include…

A

1) Lactate dehydrogenase (LDH)
2) Creatine Kinase (CK)
3) Alkaline phosphatase
4) Acid Phosphatase

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4
Q

What are the three characteristics of LDH isoenzyme

A

1) tetramer
2) 4 protein subunits, each called a protomer. Two types: Heart and muscle
3) 5 types of isoenzymes

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5
Q

What are the 5 types of LDH isoenzyme

A

1) LDH1 (HHHH)
2) LDH2 (MHHH)
3) LDH3 (MMHH)
4) LDH4 (MMMH)
5) LDH5 (MMMM)

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6
Q

What disease does LHD3 increase in

A

Leukemia

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7
Q

What disease does LDH1 increase in

A

Myocardial infarction

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8
Q

What disease does LDH4 increase in

A

Viral hepatitis

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9
Q

What disease does LDH2 increase in

A

Myocardial infarction

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10
Q

What disease does LDH5 increase in

A

Viral hepatitis

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11
Q

What is the normal LDH1-2 level

A

LDH2>LDH1

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12
Q

What is the flipped LDH ratio and what is its diagnoses

A

LDH1>LDH2
Ischemic heart disease

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13
Q

What’s the purpose of LDH in diagnoses

A

Diagnostic measure to differentiate between heart, liver, and blood diseases

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14
Q

What are the three characteristics of CK

A

1) dimer
2) 2 protein subunits. Types: Brain & muscle (true isomers)
3) 3 isoenzymes

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15
Q

What are the three isoenzymes of CK

A

1) CK BB
2) CK MB
3) CK MM

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16
Q

What disease does CK BB increase in

A

Brain tumors

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17
Q

What disease does CK MB increase in

A

Heart diseases

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18
Q

What disease does CK MM increase in

A

Skeletal muscle diseases

19
Q

Why are CK isoenzymes important

A

To differentiate between brain, heart, and skeletal muscle diseases.

20
Q

Two sources of isoenzymes

A

1) true genetic variants (true isoenzymes): may be produced by more than one gene, each gene responsible for one subunit.
2) multiple forms (post translational modification): may be produced by the same gene but each subunit undergoes different post translational modifications for each different organ.

21
Q

Two types of plasma enzymes

A

Functional and nonfunctional plasma enzymes

22
Q

Concentration in plasma of functional VS nonfunctional plasma enzymes

A

Functional: high concentration in plasma
Nonfunctional: low concentration in plasma

23
Q

Functional plasma enzymes substrate presence in blood VS nonfunctional

A

Functional: substrates always present in blood.
Nonfunctional: substrates normally absent in blood.

24
Q

Site of synthesis of functional VS nonfunctional plasma enzymes

A

Functional: Liver
Nonfunctional: different organs like liver, heart, brain, skeletal muscle.

25
Q

Site of synthesis of functional VS nonfunctional plasma enzymes

A

Functional: Liver
Nonfunctional: different organs like liver, heart, brain, skeletal muscle.

26
Q

Effect of diseases on functional vs nonfunctional plasma enzymes

A

Functional: decreases in liver disease
Nonfunctional: increases in different organ diseases.

27
Q

Examples of functional plasma enzymes (3)

A

1) clotting factor (prothrombin)
2) lipoprotein lipase
3) pseudo-choline estrase

28
Q

Examples of non functional plasma enzymes (6)

A

1) Alenine transaminase (ALT)
2) Aspartate transaminase (AST)
3) CK, LDH
4) Alkaline phosphatase (ALP)
5) Amylase
6) Lipase

29
Q

What are the three sources of non functional plasma enzymes

A

1) obstruction of normal pathway (ALP)
2) increases permeability of cell mb. (Tissue hypoxia, LDH)
3) cell damage (release of its enzymes its blood)

30
Q

Medical importance of non functional plasma enzymes

A

Diagnoses, prognoses, and regulation of enzyme activity.

31
Q

What disease do amylase and lipase determine

A

Pancreatitis

32
Q

What diseases does CK help determine

A

Heart, brain, skeletal muscle diseases.

33
Q

What diseases does LDH help determine

A

Heart, liver, and blood diseases

34
Q

What diseases does ALT (SGPT) help determine

A

Liver disease

35
Q

What diseases does AST (SGOT) help determine

A

Liver and heart diseases

36
Q

What are the two ways of enzyme regulation

A

1) change in amount of enzyme (long term regulation)
2)control in enzyme activity (short term regulation)

37
Q

The amount of enzyme depends on…

A

Rate of enzyme synthesis and rate of enzyme degradation

38
Q

An amount of enzyme is raised by… and decreased by…

A

Raised: induction of gene (increase in synthesis)
Decreased: repression of gene (decrease in synthesis)

39
Q

Three ways to control enzyme activity are

A

1) allosteric effectors
2) covalent modification
3) limited proteolysis

40
Q

What are allosteric effectors

A
  • way of enzyme regulation by regulation catalytic activity.
    -low molecular weight compounds
  • attach to allosteric site
  • little/ no structural similarity of substrate of enzyme
  • Example: feedback inhibition
41
Q

What is covalent modification

A

-way of enzyme regulation by the control of enzyme activity
- covalent attachment of phosphate group.
- enzymes called inconvertible enzymes, could be high or low catalytic efficiency
- phospho or dephosphoenzyme could be more or less active depending on enzyme activity.
- phospho/ dephosphorelation is catalyzed by protein kinase and protein phosphatase.

42
Q

What is limited proteolysis

A
  • way of regulating enzymes by control of enzyme activity
  • Proteolysis: Converting inactive proenzyme to active.
    Accompanied by conformational changes that either reveal or change active site.
43
Q

Synthesis as an inactive proenzyme if a characteristic of which three enzymes

A

1) protein digestive enzymes
2) enzymes of blood coagulation
3) zymogens (enzymes of blood clot dissolution/ anticoagulants)
4) Pepsin

Biochemistry (2 decks)

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