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yr 1 uni work > 115 > Flashcards

115 Flashcards

1
Q

2 major functions of HSA

A
  1. as a transporter of smaller, mostly hydrophobic molecules
  2. as the major contributor (80%) of the osmotic swelling pressure of blood plasma
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2
Q

where does albumin rapidly migrate

A

positive electrode

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3
Q

forest plot

A

A forest plot is often used in a meta-analysis of the effect of perhaps a drug or a treatment. This type of analysis takes lots of studies which have examined the same thing, and shows the outcome of each, and of them all added together.

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4
Q

a-domain structure

A

commonly in proteins its found in isolated a-helices but this isn’t that stable so a-helices tend to be packed pairwise in proteins with their hydrophobic residues pointing towards the molecules core

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5
Q

HSA Mr

A

66 500

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6
Q

HSA pl

A

5.67

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7
Q

HSA structure

A

single polypeptide chain
585 amino acids with 17 intra-chain disulphide bonds
These disulfide bonds pull the molecule into a series of large (L) and small (S) double loops.
Not only are there three similar domains but examination of the amino acid sequence shows that there are repetitions even from one individual loop to another.

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8
Q

The AA sequence of albumin has an unusually high percentage of Cys (35 out of 585 amino acids).
true or false

A

true

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9
Q

in circulating plasma how much of free sulfhydryl Cys-34 is oxidised

A

30%

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10
Q

does albumin contain multiple binding sites

A

yes - notable for long-chain fatty acids, small heterocyclic or aromatic carboxylic acids and for metals

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11
Q

what ions can cys-34 (SH-group) bind

A

Cd, Au, Hg, Ag

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12
Q

what does N-terminal His-3 bind in albumin acting as a transporter

A

Cu(II), Ni (II)

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13
Q

examples of drugs that are transported by albumin

A

aspirin
AZT
penicillin and Warfarin

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14
Q

why is drugs transported by albumin pharmacologically important

A

This is pharmacologically important as drugs compete for binding sites and small molecules, not transported on proteins, may be excreted by the kidney into the urine.

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15
Q

what does serum albumin (1e7a) bind to

A

propofol (an anaesthetic)

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16
Q

what does serum albumin (1e7b) bind to

A

halothane (an anaesthetic)

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17
Q

does evans blue have a high affinity for serum albumin

A

yes

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18
Q

serum albumin excitation peaks - evans blue

A

peaks at 470nm and 540nm and an emission peak at 680nm

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19
Q

what is evans blue used as

A

viability assay
permeability of the blood-brain barrier to macromolecules

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20
Q

which of the following are albumin functions
structural
catalytic
second messenger
transport
oncotic regulator

A

transport
oncotic regulator

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21
Q

human serum albumin is rich in what

A

a-helices
disulphide bonds

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22
Q

can albumin transport different substances in several sites of its structure

A

yes

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23
Q

what organ is responsible for synthesising HSA

A

liver

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24
Q

the EF hand overview

A

associated with ca+ binding

named from the Ca2+ binding site between the E and F a-helices in parvalbumin.

A HELIX-LOOP-HELIX configuration characterises the EF hand

25
Q

whats a motif

A

a conserved amino acid sequence alignment- a local alignment corresponding to a region whose function or structure is known, or its significance may be unknown

26
Q

Kd definitition

A

it is a measure of the affinity between 2 molecuels
The Kd is the concentration at which 50% of the ligand is free and 50% is bound to a receptor.

27
Q

if the Kd is low then the affinity of the ligand for the receptor is very what ?

A

high

28
Q

if the Kd is high then the affinity of the ligand for the recepter is what ?

A

very low

29
Q

at ligand conc above the Kd where is most the ligand

A

bound to the receptor

30
Q

at the ligand conc below the Kd where is most of the ligand

A

its free

31
Q

where are members of the superfamily of EF-hand containing proteins found

A

in the cytosol

32
Q

what affinity does EF-hand containing proteins bind calcium

A

Kd of around 10^-6

33
Q

extracellular [Ca+] M

A

10^-3

34
Q

intracellular (unstimulated) [Ca+] M

A

10^-7

35
Q

intracellular (stimulated) [Ca+] M

A

10^-5/ 10^-6

36
Q

how many residues does EF-hand contain

A

29 resdidues

37
Q

what amino acid is at position one in the first a-helix of the EF-hand

A

Glu

38
Q

positions of hydrophobic residues facing the core of the molecules (first a-helix)

A

2,5,6,9

39
Q

position of glu and residues on the second a-helix of EF-hand

A

glu at psotion 21
residues at 22,25,26,29 and they are hydrophobic

40
Q

Acidic amino acids have carboxylate oxygen atoms that can ligate calcium.
true or false

A

true

41
Q

Glycine found at position 15 permits a soft bend. in EF-hand
true or false

A

false
its a sharp bend

42
Q

calmodulin overview

A

CALMODULIN is a 17 kDa protein with a highly conserved amino acid sequence which contains 4 EF hands.
Following calcium binding it changes shape and is able to bind to and activate kinases.

43
Q

is calcium ion an important secondary messenger invovled in muscle contraction

A

yes

44
Q

does calcium ion control reease of hormones and neurotransmitters

A

yes

45
Q

do many Ca+ bidning proteins contain an EF hand

A

yes

46
Q

calmodulin isnt one of the main effectors of ca2+ signalling
true or false

A

false
it is one of the main effectors

47
Q

is Ca+ and EF hand motif involved in binding of carbs by lectins

A

yes

48
Q

what shape is calmodulin

A

dumbbell shape

49
Q

where are the EF-hands on calmodulin

A

The N- and C-terminal domains each have 2 EF hands (EF1–4) separated by a unique 6-turn single a-helix.

50
Q

do EF hands occur lone or in pairs

A

EF hands generally occur in pairs within globular domains and there is cooperative calcium binding.

51
Q

apo definition

A

an apo structure is missing its ligand or binding partner

52
Q

binding of calcium to calmodulin causes a conformational change
true or flase

A

true
exposing hydrophobic patch in each globular domain

53
Q

what do ydrophobic patches in calmodulin and ca+ bidning allow

A

interactions with other proteins

54
Q

hydrophobic patches binding target peptides

A

long helix of the dumb-bell unwinds and the two lobes of calmodulin swing around to enfold the a-helical target peptide.
A hydrophobic patch on each lobe of the calmodulin contacts the hydrophobic side of the helical target peptide.
Thus, the target peptide sits in a hydrophobic channel.

55
Q

examples of target enzymes for calmodulin and ca+ binding

A

Phosphorylase kinase, myosin light chain kinase, adenylate cyclases and the Ca2+ ATP-ase.
Target enzymes have a mixture of basic and hydrophobic amino acids which are capable of adopting an a-helix.

56
Q

how many EF hands does calmodulin have

A

4 each bind ca2+

57
Q

is calmodulin a sensor

A

yes- is a sensor of an increase in intracellular [Ca2+], and calcium enhances its affinity for a number of important regulatory proteins.

58
Q
A

yr 1 uni work (13 decks)

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