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Biochem Exam 3 > Conversion of AAs to Specialized Products > Flashcards

Conversion of AAs to Specialized Products Flashcards

1
Q

What are the 3 sources of our AA pool?

A

1) Diet
2) Actual body protein
3) Synthesis of non-essential AAs that we make

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2
Q

What is the most common porphyrin in humans?

A

Heme

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3
Q

What is a porphyrin?

A

Cyclic compounds that binds metal ions (usually Fe2+ or Fe3+)

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4
Q

What many roles does heme have?

A

Hemoglobin, myoglobin, cytochromes, cytochrome P450 monooxygenase system, catalase, NO synthase and peroxidase

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5
Q

What are the major sites of heme biosynthesis?

A

Liver and erythrocyte-producing cells of bone marrow

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6
Q

What specific AA do we use for the making of heme?

A

Glycine

-Glycine is combined w/ succinyl CoA

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7
Q

What is the most important, rate-limiting, committed step of the making of heme?

A

ALAS1

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8
Q

What is heme biosynthesis inhibited by?

A

Heme

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9
Q

What is the 2nd step of heme biosynthesis (ALA to Porphobilinogen) inhibited by?

A

Lead

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10
Q

What is the last enzyme of heme biosynthesis?

A

Ferrochelastase (mitochondrial enzyme)

-Protoporphyrin IX -> Heme (iron is just added to center with N’s pointing in attached to it)

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11
Q

What is the last step of heme biosynthesis inhibited by?

A

Lead

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12
Q

What is porphyrias?

A

Rare, inherited defects in heme synthesis -> accumulation and increased excretion of porphyrins or porphyrin precursors

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13
Q

How long does a RBC live? Where is it degraded?

A

120 days

-Degraded in liver and spleen

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14
Q

What is the first step of heme degradation?

A

An old heme is picked up by a macrophage in spleen -> Heme oxygenase breaks open the heme (using NADPH) -> Biliverdin (green pigment)

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15
Q

What happens to biliverdin?

A

Reduced to bilirubin (red-orange) by biliverdin reductase (using NADPH)

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16
Q

What happens to bilirubin?

A

It is too hydrophobic, so attaches to albumin -> complex travels to liver

17
Q

What happens to the bilirubin in the liver in order to make it more soluble and easier to eliminate?

A

A conjugation adds 2 acidic sugars (UDP-glucuronic acid) to bilirubin to form bilirubin diglucoronide

18
Q

What gives urine its yellow color?

A

As bile goes through the intestine, bacteria deconjugates it -> urobilinogen in colon -> some goes to kidney -> urobilin

19
Q

What gives feces its brown color?

A

Rest of urobilinogen in colon becomes oxidized by intestinal bacteria -> stercobilin

20
Q

What is hyperbilirubinemia?

A

High [bilirubin] in blood -> Yellow color of skin, nail beds and sclerae

21
Q

Why are premature babies more likely to get jaundice?

A

Have less of Bilirubin UDP-glucuronosyltransferase (bilirubin UGT) -> enzyme that makes bilirubin more soluble by conjugation

  • Serum levels of bilirubin will be too high
  • Tx: UV light has direct impact on bilirubin (modifies it to make it more soluble)
22
Q

What are 5 other N-containing compounds?

A

1) Catecholamines
2) Histamine
3) Serotonin
4) Creatine
5) Melanin

23
Q

What are the catecholamines?

A

Dopamine, Norepinephrine, Epinephrine

-All biologically active amines

24
Q

What are the catecholamines made from?

A

Tyrosine

25
Q

What is the role of dopamine and NE?

A

Brain neurotransmitters

26
Q

What are NE and Epi involved in?

A

Hormone regulators of carbs and lipids’ metabolism outside CNS

27
Q

What does histamine mediate?

A

Allergic and inflammatory reactions and gastric acid secretion

28
Q

What is histamine made from?

A

Decarboxylation of histidine (requires PLP)

29
Q

What is a function of histamine?

A

Powerful vasodilator

30
Q

What is serotonin synthesized from?

A

Tryptophan

31
Q

What does serotonin mediate?

A 
Pain perception
Regulation of sleep
Appetite
Temperature
BP
Cognitive functions
Mood
32
Q

What do SSRIs maintain?

A

Levels of serotonin

-Selective serotonin reuptake inhibitors

33
Q

What does creatine come from?

A

From arginine and glycine (in the kidney)

34
Q

What does creatine phosphate provide?

A

Small reserve for ATP in muscle

-Creatine kinase will take ATP and store it in creatine phosphate

35
Q

What is melanin?

A

Pigment in the eye, hair and skin

36
Q

What is melanin synthesized from?

A

Tyrosine in melanocytes of the epidermis

37
Q

What is the function of melanin?

A

To protect underlying cells from harmful effects of sunlight

Biochem Exam 3 (7 decks)

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