115

Question 1

2 major functions of HSA

Answer 1

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

Question 2

where does albumin rapidly migrate

Answer 2

positive electrode

Question 3

forest plot

Answer 3

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.

Question 4

a-domain structure

Answer 4

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

Question 5

HSA Mr

Answer 5

66 500

Question 6

HSA pl

Answer 6

5.67

Question 7

HSA structure

Answer 7

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.

Question 8

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

Answer 8

true

Question 9

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

Answer 9

30%

Question 10

does albumin contain multiple binding sites

Answer 10

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

Question 11

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

Answer 11

Cd, Au, Hg, Ag

Question 12

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

Answer 12

Cu(II), Ni (II)

Question 13

examples of drugs that are transported by albumin

Answer 13

aspirin
AZT
penicillin and Warfarin

Question 14

why is drugs transported by albumin pharmacologically important

Answer 14

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.

Question 15

what does serum albumin (1e7a) bind to

Answer 15

propofol (an anaesthetic)

Question 16

what does serum albumin (1e7b) bind to

Answer 16

halothane (an anaesthetic)

Question 17

does evans blue have a high affinity for serum albumin

Answer 17

yes

Question 18

serum albumin excitation peaks - evans blue

Answer 18

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

Question 19

what is evans blue used as

Answer 19

viability assay
permeability of the blood-brain barrier to macromolecules

Question 20

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

Answer 20

transport
oncotic regulator

Question 21

human serum albumin is rich in what

Answer 21

a-helices
disulphide bonds

Question 22

can albumin transport different substances in several sites of its structure

Answer 22

yes

Question 23

what organ is responsible for synthesising HSA

Answer 23

liver

Question 24

the EF hand overview

Answer 24

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

Question 25

whats a motif

Answer 25

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

Question 26

Kd definitition

Answer 26

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.

Question 27

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

Answer 27

high

Question 28

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

Answer 28

very low

Question 29

at ligand conc above the Kd where is most the ligand

Answer 29

bound to the receptor

Question 30

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

Answer 30

its free

Question 31

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

Answer 31

in the cytosol

Question 32

what affinity does EF-hand containing proteins bind calcium

Answer 32

Kd of around 10^-6

Question 33

extracellular [Ca+] M

Answer 33

10^-3

Question 34

intracellular (unstimulated) [Ca+] M

Answer 34

10^-7

Question 35

intracellular (stimulated) [Ca+] M

Answer 35

10^-5/ 10^-6

Question 36

how many residues does EF-hand contain

Answer 36

29 resdidues

Question 37

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

Answer 37

Glu

Question 38

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

Answer 38

2,5,6,9

Question 39

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

Answer 39

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

Question 40

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

Answer 40

true

Question 41

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

Answer 41

false its a sharp bend

Question 42

calmodulin overview

Answer 42

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.

Question 43

is calcium ion an important secondary messenger invovled in muscle contraction

Answer 43

yes

Question 44

does calcium ion control reease of hormones and neurotransmitters

Answer 44

yes

Question 45

do many Ca+ bidning proteins contain an EF hand

Answer 45

yes

Question 46

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

Answer 46

false it is one of the main effectors

Question 47

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

Answer 47

yes

Question 48

what shape is calmodulin

Answer 48

dumbbell shape

Question 49

where are the EF-hands on calmodulin

Answer 49

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

Question 50

do EF hands occur lone or in pairs

Answer 50

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

Question 51

apo definition

Answer 51

an apo structure is missing its ligand or binding partner

Question 52

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

Answer 52

true exposing hydrophobic patch in each globular domain

Question 53

what do ydrophobic patches in calmodulin and ca+ bidning allow

Answer 53

interactions with other proteins

Question 54

hydrophobic patches binding target peptides

Answer 54

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.

Question 55

examples of target enzymes for calmodulin and ca+ binding

Answer 55

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.

Question 56

how many EF hands does calmodulin have

Answer 56

4 each bind ca2+

Question 57

is calmodulin a sensor

Answer 57

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