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MSAP Review > Respiratory Biochemistry > Flashcards

Respiratory Biochemistry Flashcards

1
Q

Primary Structure

A

Sequence of amino acids by polypeptide bonding (N-terminus to C-terminus)

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2
Q

Secondary Structure

A
  • Alpha-Helix (Side chains stick out and hydrogen bonding parallel)
  • Beta-Sheet (Side chains stick in and out and hydrogen bonds form in “middle”)
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3
Q

Tertiary Structure

A
  • Formed by a folding of a secondary structure on top of itself.
  • Creation of a 3D structure (and protein shape)
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4
Q

Quaternary Structure

A

Two or more polypeptides coming together.

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5
Q

Globular Proteins

A
  • Water soluble (hydrophilic) proteins and are therefore have polar side chains on surface.
  • Nonpolar side chains are in the interior. Creation of “hydrophobic core”
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6
Q

Function of Globular Proteins

A

Catalysis, regulation, and transport within body.

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7
Q

How is the alpha helix stabilized?

A

By hydrogen bonds within the peptide chain.

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8
Q

How are tertiary structures stabilized?

A

1) By hydrogen bonding b/w amino acid side chains.
2) Disulfide bond formation (from two cysteine amino acids).
3) Ionic Interaction b/w two charged amino acids.

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9
Q

Function of hemoglobin

A

To transfer oxygen in body to tissue

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10
Q

Why is free oxygen dangerous in the body

A

B/c it is somewhat toxic b/c of oxidizing behavior.

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11
Q

What is heme (general)?

A

Heme is a prosthetic group (not a part of proteins structure). It binds to the globin (globular protein) in order to aid in the transfer of oxygen in the body.

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12
Q

Why is heme so important?

A

B/c oxygen is so toxic, the heme protects against the radioactive oxygen. Specifically, the ferrous ion minimizes the “dangerous” chemistry.

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13
Q

What is heme comprised of?

A

Porphyrin Ring + Ferrous iron (Fe 2+)

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14
Q

Describe porphyrin

A

Nitrogenous ringed structure

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15
Q

Cells that have heme containing proteins MUST also contain:

A

Mitochondria

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16
Q

Name two examples of globular hemeproteins:

A

1) Hemoglobin

2) Myoglobin

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17
Q

Where is myoglobin found?

A

In the muscle

18
Q

Describe the structure of myoglobin

A

Made of ONE (a-helix) polypeptide chain (tertiary)

There is one heme group attached to this one subunit

19
Q

Describe the structure of hemoglobin

A

Made of FOUR polypeptide chains (subunits).

Subunits:

1) a1 (with attached heme)
2) a2 (with attached heme)
3) b1 (with attached heme)
4) b2 (with attached heme)

FOUR subunits => TETRAMER

Each subunit will have a heme bound to it.

Specifically there are TWO DIMERS associated with hb. a1ba and a2b2

20
Q

Describe the bonds found in hemoglobin

A

Dimers (a1b1 and a2b2) will have STRONG hydrophobic interactions with themselves separate.

However, both dimers will form a WEAK hydrogen bond and ionic bonds that keep both dimers attached to each other and form the tetramer.

Visualization: Double forearm technique.

21
Q

How is heme bond to the globin (either in myoglobin and hemoglobin)

A

1) Histidine covalent bond to ferrous ion

2) Hydrophobic interactions

22
Q

How many oxygens can be carried on myoglobin?

A

One

23
Q

How many oxygens can be carried on Hemoglobin?

A

Four

24
Q

What is the function of myoglobin

A

Store oxygen

25
Q

Where is hemoglobin found

A

In blood

26
Q

When hemoglobin is in the taut state we assume

A

low oxygen presence (wants to be giving off oxygen).

27
Q

When hemoglobin is in the relaxed state we assume

A

high presence of oxygen (wants to be taking in oxygen)

28
Q

Hydrophobic interaction between the dimers of hemoglobin will require what type of amino acids

A

Nonpolar amino acids

29
Q

What amino acids have hydrophobic side chains

A 
Vicken Told Loucine: "I Tried Pie"
X          X     X              XX       X
Made Alexia Punch Grandpa
X        X      X          X
Valine
Tyrosine
Leucine
Isoleucine
Tryptophan
Phenylalanine
Methionine
Alanine
Proline
Glycine
30
Q

When O2 binds to heme what conformational change do we see

A

(Nonplanar => Planar)
(Taut=>Relaxed)
(Deoxygenated=> Oxygenated)

31
Q

Describe the saturation curve of hemoglobin vs myoglobin.

A

Hemoglobin is sigmoidal
Myoglobin is hyperbolic

Myoglobin has a higher affinity (shifted left than hemoglobin)

See slide 45 of RESP. BIOCHEM

32
Q

Explain the sigmoidal behavior of hemoglobin

A

COOPERATIVE LIGAND BINDING.

Affinity starts low but as o2 binds to hb, the hb gets very hungry and more binding ensues. A leveling off of affinity eventually happens.

33
Q

Name 4 things that can affect hb affinity

A

1) pH
2) CO2
3) Body Temperature
4) 2-3 bisphosphoglycerate

34
Q

Decrease of pH does what to hemoglobin

A

Decrease in pH causes the hemoglobin to be in a charged state.

Charged state => bond holding ab dimers to form tetramer got a whole lot stronger

This charged state => taut state.

Taut state means that hb has low affinity for O2 and wants to transport it to tissue.

35
Q

Increase in pH does what to hemoglobin

A

Increase in pH causes the hemoglobin to be in an uncharged state (between the bond forming the tetramer)

Uncharged state => relaxation state.

Affinity of hemoglobin to o2 goes up and hemoglobin was to hold onto o2 rather than give it up to tissue.

36
Q

Bohr Affect

A

The Bohr Effect refers to the observation that increases in the carbon dioxide partial pressure of blood or decreases in blood pH result in a lower affinity of hemoglobin for oxygen.

37
Q

What is 2-3 bisphosphoglycerate

A

A substrate produced from a side reaction of glycolysis.

2-3 bpg is a highly negative charged substrate

38
Q

Function of 2-3 bpg

A

Potent regulator of hb o2 affinity. If bound to charge hydrogen bonds and ionic bonds of hb tetramer, THIS drives taut state.

HIGH 2-3 BPG => TAUT STATE => Hb LOW AFFINITY TO O2 => RELEASE of O2 to tissue,

39
Q

Relationship of hemoglobin to myoglobin

A

Hemoglobin transfers O2 to myoglobin. Myoglobin stores the o2 till the muscles need it (Myoglobin gives to mitochondria of cell)

40
Q

Bonds that ferrous ion forms in Hb

A

Ferrous ion forms a total of 6 bonds:

4 bonds => porphyrin ring
1 bond => proximal histidine
1 bond => reversible oxygen binding

41
Q

Differences between fibrous and globular proteins.

A

Fibrous:

  • looks like rope
  • structural
  • hold a secondary structure
  • stabilized by hydrogen bonds
  • held by a parallel polypeptide bond
  • insoluble in water

Globular:

  • looks like globe
  • tertiary or quaternary
  • stabilized by disulfide bonds, ionic interactions, hydrogen bonds, metallic bonds, and hydrophobic interactions
  • soluble in water
42
Q

What amino acid acts as a good acid base buffer

A

Histidine

MSAP Review (5 decks)

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