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BIOCHEM 2 > Chapter 9 Protein Regulation Part II > Flashcards

Chapter 9 Protein Regulation Part II Flashcards

1
Q

What is the function of amino acids besides being the building blocks for peptides and proteins?

A

Amino acids may be oxidized for fuel.

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2
Q

What is the cofactor we will explore in this chapter?

A

The pyridoxal phosphate.

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3
Q

From what vitamin is the cofactor pyridoxal pyrophosphate derived?

A

Vitamin B6. Vitamin B6 is converted to the aldehyde and phosphorylated to form the cofactor pyridoxal pyrophosphate.

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4
Q

How is the cofactor attached to the enzymes that require this cofactor?

A

Schiff base.

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5
Q

Ammonotelic

A

excess ammonia directly flushed into the surrounding water.

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6
Q

Ureotelic

A

organisms that convert ammonia to urea.

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7
Q

Uricotelic

A

organisms that convert ammonia to uric acid.

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8
Q

Why do we make urea?

A

ammonia within the body must be eliminated.

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9
Q

What is the source of the nitrogen in urea biosynthesis?

A

amino acids.

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10
Q

What are the central four amino acids of nitrogen metabolism?

A

glutamate

glutamine

alanine

aspartate

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11
Q

What molecule forms when amino group is freed from glutamate?

A

alpha-ketoglutarate

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12
Q

What molecule forms when amino group is freed from glutamine?

A

alpha-ketoglutarate

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13
Q

What molecule forms when amino group is freed from alanine?

A

pyruvate

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14
Q

What molecule forms when amino group is freed from aspartate?

A

oxaloacetate

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15
Q

In what organ does amino acid catabolism take place?

A

Liver

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16
Q

Chemical Mechanism for amino acid decarboxylation

A

refer to slides

17
Q

Chemical Mechanism for amino acid racemization

A

refer to slides.

18
Q

What is the role of the pyridoxal phosphate?

A

temporarily store these electrons through resonance stabilization.

19
Q

In what form is most of the nitrogen from skeletal muscle transferred to the liver?

A

alanine

20
Q

In what form is most of the nitrogen from some muscle and other metabolically active tissues transported to the liver?

A

glutamine

21
Q

Write mechanism of transamination

A

refer to slides.

22
Q

How are amino groups liberated from glutamate in the liver? What cofactor is required for this process?

A

through the enzyme L-glutamate dehydrogenase.

cofactor: NAD+ or NADP+

23
Q

What are allosteric regulators of L-glutamate dehydrogenase?

A

ADP positive allosteric modulator

GTP negative allosteric modulator

24
Q

What is the intercellular transport molecule that carries much of the excess ammonia from the tissues to the liver?

A

glutamine

25
Q

What is the mechanism for carrying excess ammonia from the muscle to the liver?

A

Phosphorylation of the side chain carboxyl in glutamate and glutamine creates a good leaving group. Nitrogen of ammonia acts a nucleophile to displace the inorganic phosphate.

26
Q

Which molecule provides the carbon for urea in the urea cycle?

A

bicarbonate.

27
Q

What is the origin of the first and second nitrogen atoms in the urea cycle?

A

First: ammonia

Second: aspartic acid

28
Q

What is the origin of the oxygen?

A

water

29
Q

How is the balance of nitrogen maintained through both sides of the mitochondrial matrix?

A

Through the aspartate-glutamate antiporter, for every aspartate that is leaving glutamate carries new nitrogen to regenerate ammonia population.

30
Q

How is the balance of carbon maintained through both sides of the mitochondrial matrix?

A

Through the ornithine-citruline antiporter, for every citruline that leaves ornithine enters maintaining the carbon balance.

31
Q

What is the role of the first two ATP consumed in the urea cycle?

A
  1. ATP activates bicarbonate.
  2. ATP activates carbamide.
32
Q

What is the role of the third ATP?

A

Third ATP activates citruline forming citrullyl-AMP intermediate.

33
Q

Name the major allosteric regulator of the urea cycle.

A

N-acetyl glutamate.

34
Q

Explain what enzyme N-acetyl glutamate regulates and how?

A

N-acetyl glutamate regulates the carbomoyl phosphate synthase-I. N-acetyl glutamate is a positive allosteric regulator of the urea cycle.

35
Q

Explain what enzyme N-acetyl glutamate regulates and how?

A

N-acetyl glutamate regulates the carbomoyl phosphate synthase-I. N-acetyl glutamate is a positive allosteric regulator of the urea cycle.

N-acetyl glutamate is produced from acetyl coA and glutamate. Therefore, when these compounds are abundant there is a need for the urea cycle.

36
Q

What are other ways in which the urea cycle is regulated?

A

substrate availability and enzyme synthesis turnover.

More protein we eat more urea generated.

37
Q

How are urea cycle disorders treated?

A

Limiting protein intake.

BIOCHEM 2 (17 decks)

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