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Biochemistry > Globular Proteins > Flashcards

Globular Proteins Flashcards

1
Q

Structure of protein which is the result of H-bonding producing regular repeated structure

A

Secondary structure

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2
Q

What are the two heme proteins?

A

Hemoglobin and myoglobin

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3
Q

How many Oxygen binds to hemoglobin

A

4

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4
Q

What is the structure of heme?

A

Complex of protoporphyrin IX and ferrous iron (Fe2+)

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5
Q

Heme is also called __________ because iron is held by 4 nitrogen of porphyrin ring

A

Tetrapyrrole

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6
Q

What links the 4 molecules of pyrrole?

A

A-methylyne bridges

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7
Q

The organic component protoporphyrin is made up of?

A
  • 4 pyrrole rings
  • 4 methyl groups
  • 2 vinyl groups
  • 2 propionate
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8
Q

The central iron is normally of _______ form or oxidized state

A

Ferrous

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9
Q

Monomeric heme found in muscle tissue where it serves as an intracellular storage site of oxygen

A

Myoglobin

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10
Q

Myoglobin secondary structure contains how many percent of A- helices?

A

75%

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11
Q

Myoglobin is comprised of how many separate right handed A-helices?

A

8

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12
Q

R-groups in the surface of the molecule are generally ___________, making the molecule relatively water soluble

A

Hydrophilic

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13
Q

Structure of proteins composed of sequence of amino acids

A

Primary structure

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14
Q

The oxygen binding site contains heme prosthetic grp with Fe in the center and __________ residues located above and below

A

Histidine

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15
Q

Oxidation of iron int what state renders the molecule incapable of normal oxygen binding

A

Ferric Fe3+

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16
Q

The proximal histidine is also termed?

A

His F8 or His 93

17
Q

The iron forms additional bond with the proximal histidine on the ___________.

A

5th coordinating position

18
Q

What stabilizes the oxygen bound to the iron atom on the 6th coordinating position?

A

Distal histidine residue or His E7 or His 64

19
Q

Heme part of hemoglobin is synthesized in the _______ and ________ of immature cells, while _______ protein are synthesized by ribosones in cytosol.

A

Mitochondria and cytosol

Globin

20
Q

What composes hemoglobin?

A

2 Alpha and 2 Beta polypeptide chain

21
Q

The capacity of hemoglobin to bind oxygen depends on the presence of __________.

A

Heme

22
Q

In hemoglobin, the 5th coordination site is occupied by ___________ of histidine residue

A

Imidazole ring

23
Q

A state of hemoglobinwhere the 6 th coordination site is unoccupied.

A

Deoxyhemoglobin

24
Q

In hemoglobin, the iron lies approximately ______ outside the porphyrin plane because iron is slightly too large to fit into the well defined hole

A

0.4 A

25
Q

What happens when oxygen bind to the iron atom?

A

The iron atom is pulled towards the plane of the heme

26
Q

On oxygenation, 1 pair of alpha-Beta subunits shifts with respect to the other by a rotation of _________.

A

15 degrees

27
Q

What are the effects of oxygen binding in deoxyhemoglobin?

A

Conformational change at F8 is transmitted in the peptide backbone changing the tertiary structure. Disruption of salt bridges and formation of new hydrogen bonds and new hydrophobic interactions contribute to new quarternary structure

28
Q

What happens when oxygen binds to the first subunit of deoxyhemoglobin?

A

This increases the affinity of remaining subunits for oxygen

29
Q

It is the tertiary configuration of low affinity, deoxygenated Hb

A

Taut state

30
Q

The quarternary stucture of the fully oxygenated high affinity form of Hb

A

Relaxed state

31
Q

True or False: salt bridges of T structure increases as oxygen is added

A

False

32
Q

Transition is influenced by protons, CO2, Cl, BPG. The higher their conc, the greater is the tendency towards what form of Hb?

A

Taut state

33
Q

The ability of Hg to bind to O2 is affected by ________. These include pO2, pH, pCO2, 2,3-BPG

A

Allosteric effectors

34
Q

What is the shape of the curve of oxygen binding to Hb?

A

Sigmoidal

35
Q

True or false: when there is increased H+, there is a decrease in pH. Because pH is directly proprtional to oxgen affinity, there is low oxygen affinity and release of oxygen.

A

True

36
Q

What happens when there is an increase in CO2?

A

CO2 diffuses into the blood, it is formed carbonic acid with H2O thru carbonic anhydrase, and further converted to bicarbonate ion and H+ by spontaneous rxn, therefore also increasing H+ in the blood

37
Q

The transport of CO2 as bicarbonate ion in the blood is referred to as__________.

A

Isohydric transport

38
Q

Form of CO2 transported in the blood as dissolved gas formed with N terminal amino grps of the T form of Hb.

A

Carbaminohemoglobin

39
Q

Decrease in blood pH or increase in blood CO2 conc

A

Bohr effect

Biochemistry (4 decks)

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