Biochemistry- Amino Acids and Proteins Flashcards Preview

NPLEX I > Biochemistry- Amino Acids and Proteins > Flashcards

Flashcards in Biochemistry- Amino Acids and Proteins Deck (64)
1

Tryptophan is a precursor for what neurotransmitter?

serotonin

2

The reaction of tryptophan to serotonin requires what vitamin as a cofactor?

B6- pyrodoxine

3

Tryptophan can also be turned into what molecule?

Niacin

4

Phenylkeonturia is a genetic inability (lack of phenylalanine hydroxylase) to convert phenylalanine into what aminoacid?

Tyrosine

5

Tyrosine is the precursor for which 2 neurotransmitters and what is the intermediate substance produced?

Norepi, and Epinephrine
Dopamine intermediate

6

What is the rate-limiting enzyme for the production of L-DOPA (and therefore catecholamines in general) from tyrosine?

Tyrosine hydroxylase

7

What inhibits and promotes the activity of tyrosine hydroxylase?

Promotes: cold, stress
Inhibits: Norepi

8

What vitamin is needed as a cofactor for the production of Norepi from dopamine?

Vitamin C

9

What is the name of the enzyme that breakdown Norepi and epinephrine?

Monoamineoxidase (MAO)

10

What is the breakdown product of MAOs action of norepi and epic?

vanillmandelic acid (VMA)

11

What are the 3 branched chain amino acids?

BCAAs: valine, isoleucine, leucine

12

Post-translational modification of proline and lycine to form hydroxylycine and hydroxyproline in collagen formation requires what vitamin?

Vitamin C

13

Which are the only 3 amino acids that can be posttranvslationally modified by phosphorylation?

serine, threonine, tyrosine

14

Acetylcholine is formed from what amino acid?

Serine

15

GABA (gamma amino butyric acid) is formed from what amino acid?

Glutamate/ Glutamic acid

16

The reaction of glutamic acid to GABA requires what vitamin as a cofactor?

B6 (pyrodoxine)

17

Histamine is formed from what amino acid?

Histadine

18

Which amino acid is the main methyl donor in the body?

Methionine

19

What are the 6 amino acids that can be catabolized by skeletal muscle?

Valine
Leucine
Isoleucine
Aspartic acid
Asparagine
Glutamin Acid

20

What are the 3 amino acids that make up the tripeptide glutathione?

Cysteine, Glycine and glutamic acid

21

What are the 2 initial precursors for heme synthesis?

Glycine and succinyl CoA

22

What amino acid is the main transporter of nitrogen (ammonia) in the blood?

Glutamine

23

Alanine can be converted into what substance?

Pyruvate

24

What amino acid is a major component of actin and myosin? What form does it take?

Histadine in the form of 3-methyl histadine

25

What type of bond holds together the amino sequence of peptides?

covalent

26

what are the only 2 sulphur containing amino acids?

cysteine, methionine

27

What 2 bonds hold a secondary protein structure?

disulfide, weak covalent bonds

28

3D folding is seen is which level of protein structure?

tertiary

29

2 or more single polypeptide chains bonded by weak bonds is called what?

quaternary structure

30

Heme molecule is an example of what type of protein structure?

quaternary

31

2 cysteine resides can form what type of bond

disulfide

32

a water soluble protein is known as what?

globular, hydrophilic

33

What kinds of bonds make up secondary structure?

salt bridges, hydrophobic interactions, hydrogen bonds...

34

Atoms that share 1 or more electrons are bonded by what type of bond?

covalent

35

What are the 9 essential amino acids?

Threonine, Valine, Tryptophan, Phenylalanine, Isoleucine, Methionine, Histadine, Alanine, Leucine, Lysine
(PVT TIM HALL)

36

The removal of an alpha amino group from an amino acid is the first stage in amino acid catabolism and is known as what?

Transamination

37

Catabolism of amino acids uses what 2 types of reaction?

oxidative deamination, transamination

38

The effect of transamination reactions is to collect the amino groups from all the other amino acids in the form of only on amino acid- which one?

glutamate

39

Transaminases require what vitamin as a cofactor?

B6 (pyrodoxine)

40

Alph ketoglutarate in the alphketo acid for what amino acid?

glutamate

41

Oxaloacetate is the alphaketo acid for what amino acid?

aspartate

42

Pyruvate is the alphketo acid for what amino acid?

Alanine

43

Conversion of an amino acid into its alphaketo acid with the release of ammonia is what type of reaction?

oxidative deamination

44

Where does oxidative deamination occur?

in the liver and kidneys

45

In what part of the cell does oxidative deamination occur?

mitochondria

46

What is the main amino acid to undergo oxidative deamination?

glutamate

47

What is the main enzyme in oxidative deamination?

glutamine dehydrogenase

48

Which amino acid is present in the blood in the highest levels?

Glutamine- it is the major carrier of amino groups so toxic nitrogen can be carried in a non-toxic form from extra hepatic tissues to the liver

49

Glutamine synthetase is the enzyme that catalyzes the reaction of glutamate into glutamine. It's levels are especially high in which tissues? Why?

brain- it's especially sensitive to ammonia

50

Which amino acid transfers ammonia from the muscle to the liver?

alanine

51

Urea is formed from what 2 molecules?

CO2 and ammonia

52

Where does the urea cycle take place?

liver

53

How is the urea cycle regulated?

substrate availability ie- dietary protein

54

Where do the 2 nitrogen atoms in urea come from?

ammonia, aspartate

55

Which Krebs cycle intermediate is produced by the urea cycle?

fumarate

56

what are the 4 major constituents of urine?

urea, ammonia, creatinine, uric acid

57

What is the role of HCl in protein digestion?

denatures the protein and provides optimal pH for pepsinogen conversion to active pepsin

58

What enzyme has optimum activity at pH2?

pepsinogen/pepsin

59

What 3 aromatic amino acids have their peptide bonds hydrolyzed by pepsin?

Tyrosine, phenylalanine, tryptophan

60

Enterokinase is the enzyme that activates which zymogen released by the pancreas?

trypsinogen

61

Which enzyme activates all other enzymes released by the pancreas?

trypsin

62

What is the overall fate of proteins that we eat?

form free amino acids and enter the liver via the portal blood system

63

What is the role of brush border enzymes in protein digestion?

break down smaller peptides to release free amino acids that a readily absorbed

64

Which bonds need to be broken for a peptide to become denatured?

weak and disulfide bonds (secondary structure)