Important Enzymes Flashcards

1
Q

What is the function of hexokinase?

A

Conversion of glucose to glucose 6 phosphate in stage 1 of glycolysis or in glycogenesis tissues

Glucose + ATP –> glucose 6 phosphate + ADP

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2
Q

What is the function of glucokinase?

A

Conversion of glucose to glucose 6 phosphate in stage 1 of glycolysis or glycogenesis in liver

Glucose + ATP –> glucose 6 phosphate + ADP

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3
Q

What is the function of phosphofructokinase 1?

A

Conversion of fructose 6 phosphate to fructose 1,6 bisphosphate in step 3 of glycolysis

Fructose 6 phosphate + ATP –> fructose 1,6 bisphosphate + ADP

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4
Q

What is the function of pyruvate kinase?

A

Conversion of phosphoenol pyruvate to pyruvate in stage 10 of glycolysis

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5
Q

What is the function of lactate dehydrogenase?

A

Reduction of pyruvate to lactate in anaerobic respiration (stage 11 glycolysis)

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6
Q

What enzymes are deficient in galactosaemia?

A

Galactokinase

Galactose 1 phosphate uridyl transferase

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7
Q

Which enzyme reduced galactose to galacitol?

A

Aldose reductase

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8
Q

Where is glucose 6 phosphate dehydrogenase used?

A

In the pentose phosphate pathway

Conversion of G6P and NADP+ to C5 sugar and NADPH

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9
Q

What is the function of pyruvate dehydrogenase?

A

Converts pyruvate to acetyl~CoA to enter the TCA cycle

Irreversible

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10
Q

Where is isocitrate dehydrogenase used?

A

It is involved in the irreversible step in the TCA cycle ie production of CO2

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11
Q

What is the function of phosphoglucomutase?

A

In glycogenesis and glycogenolysis

Glucose 6 phosphate glucose 1 phosphate

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12
Q

Which enzymes are involved in adding UDP glucose to the glycogen molecule?

A

Glycogen synthase forms a 1,4 glycosidic bonds

Branching enzyme forms a 1,6 glycosidic bonds

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13
Q

Which enzymes are involved in removing glucose 1 phosphate from the glycogen molecule?

A

Glycogen phosphorylase breaks a 1,4 glycosidic bonds

Debranching enzyme breaks a 1,6 glycosidic bonds

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14
Q

What is the function of glucose 6 phosphatase and where is it found?

A

It converts glucose 6 phosphate to glucose in the liver for use as a fuel in all tissues in both glycogenolysis and gluconeogenesis

Glucose 6 phosphate + h2o –> glucose + Pi

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15
Q

What is the function of glycerol kinase?

A

Conversion of glycerol to glycerol phosphate for use in TAG synthesis or glycolysis

Glycerol + ATP –> Glycerol phosphate

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16
Q

What is the function of fatty acyl CoA synthase?

A

Activation of fatty acids in TAG metabolism
Joins CoA enzyme to S atom in fatty acid
Require ATP

17
Q

What is the function of HMG reductase?

A

Conversion of HMG~CoA to cholesterol in ketone body synthesis pathway

18
Q

What is the function of HMG lyase?

A

Conversion of HMG~CoA to ketone bodies (acetoacetate)

19
Q

What is the function of HMG synthase?

A

Addition of CoA to HMG to give HMG~CoA for ketone body synthesis.

20
Q

What is the function of fructose 1,6 bisphosphatase?

A

In gluconeogeneis, it bypasses the irreversible step 3 of glycolysis.

Fructose 1,6 bP + H2O –> fructose 6 phosphate + Pi

21
Q

What is the function of PEPCK?

A

In gluconeogeneis it is used to bypass the irreversible step 10 of glycolysis
Converts oxaloacetate to phosphoenol pyruvate using GTP

22
Q

What is the function of pyruvate carboxylase?

A

In gluconeogeneis it is used to bypass the irreversible step 10 of glycolysis
It converts pyruvate to oxaloacetate

23
Q

What is the function of fatty acid synthase?

A

Multi enzyme complex used in fatty acid synthesis to build up a fatty acid from C2 sequentially

24
Q

What is the function of acetyl~CoA carboxylase?

A

Used to produce malonyl~CoA from acetyl~CoA for fatty acid synthesis

Acetyl~CoA + CO2 + ATP –> malonyl~CoA + ADP + Pi

25
Q

What is the function of aminotransferases? Give 2 examples.

A

Used in transamination to convert an amino acid to a keto acid ie transferring the NH2 group
Alanine amino transferase (alanine –> glutamate)
Aspartate amino transferase ( glutamate –> aspartate)

26
Q

What is the function of L and D amino acid oxidises? Give 2 examples.

A

To convert amino acids to keto acids and ammonia
Glutaminase (glutamine –> glutamate)
Glutamate dehydrogenase (glutamate –> a ketoglutarate)

27
Q

What causes phenylketonuria?

A

A defect in phenylalanine hydroxylase which oxidises phenylalanine to tyrosine

28
Q

What causes homocystinuria?

A

Deficiency in cystathionine B synthase which converts homocysteine to cystathionine to cysteine

29
Q

What is the function of lipoprotein lipase?

A

Responsible for removing TAGs from lipoproteins

30
Q

What is the function of lecithin cholesterol acyltransferase?

A

LCAT converts a surface lipid to a core lipid in a lipoprotein in order to restore stability.