proteins 2

Question 1

cellular proteins

Answer 1

more than 1 polypeptide subunits

complex > 100 dK

Question 2

oligomer

Answer 2

multi-subunit complex

oligomerisation states

Question 3

homo-oligimer

Answer 3

Oligomer contains identical polypeptides

Question 4

hetero-oligimer

Answer 4

contains non-identical polypeptides

Question 5

protomers

and dimers

Answer 5

identical subunits of a complex
symmetrical unit
two monomers joined

Question 6

obligate

Answer 6

permanent interaction
can’t see them happening any other way
light and heavy chains
of antibodies

Question 7

non-obligate

Answer 7

transient
shorter interactions
RNA polymerase translating DNA temporary protein interaction

Question 8

transient and permanent interfaces

Answer 8

transient; energetically unfavourable to have hydrophobicity
permanent: hydrophobic elements unlikely that interface will be exposed to exterior

Question 9

interface

Answer 9

surfaces of the polypeptide chains
characteristics:
closely packed non-polar side chains: not exposed and allows hydrophobic interaction
hydrogen bonds: acceptors and donors : slight defamation in electron cloud could permit this
electrostatic : salt bridges ( hydrogen bounding + ion bounding)

Question 10

protein-protein interaction

Answer 10

pattern recognition process: looking for the necessary element for different bonds
complex to form orientation of all different components of the different interactions

Question 11

obligate interactions

Answer 11

hydrophobic residues present in the interface: interface will not be exposed
non polar side chain

Question 12

transient oligomers

Answer 12

fewer non polar side chains: exposed to aqueous environments
hydrophobicity at interface

Question 13

quaternary structure

Answer 13

Polypeptide subunits specific geometry in many oligomers= cyclic promoters symmetrically arranged
very complex structure = very complex function

Question 14

sub-units are potential for:

Answer 14

1) expansion,
2) easier repair (if one is damaged you can swap it out)
3) alternate site of assembly vis-à-vis production
4) reduced genetic coding (vis-à-vis 1 polypeptide)

Question 15

oligomer

Answer 15

better enzymes
protein function -
increase catalytic rate add a sub-unit
but extra complexity

Question 16

protein types

Answer 16

Fibrous Proteins secondary structure:α-helical coiled coil
globular proteins variety of secondary linked by loops
hydrophobic protein

Question 17

globular protein

Answer 17

haemoglobin:
4 subunits
adult: 2 alpha and 2 beta
foetal:2 alpha 2 gamma ( needs a greater affinity to oxygen then mother)
Iron 2+ binds oxygen Heam groups maintains Fe2+ in corrects state not Fe 3+

Question 18

co-operativity

Answer 18

4 sub units held together by electrostatic bonds enable this molecule to do this
T=taut = deoxyhemoglobin
R= relaxed= oxyhemoglobin
oxygen binds with one- change in conformation-leads others to greater affinity with oxygen
haemoglobin needs to be able to bind and release oxygen
= when one changes it’s structure influences others

Question 19

protein modification

Answer 19

particularly common post-transitional
introduced by enzymes or pathways
modifications of proteins regulators:

Question 20

modifications of proteins regulators

Answer 20

usually reversible

phosphorylation, methylation & acetylation

Question 21

regulation of destination

Answer 21

lipidation and glycolasition

Question 22

glycosylation

Answer 22

the attachment of carbohydrates common PTM’s
stabilise protein when it’s extracellular: also aids in folding and role in cell to cell recognition
50% of proteins will be glycosylysed

carbohydrates are a min component whereas in proteoglycans major component

Question 23

2 types of glycosylatio

Answer 23

N-linked NX/ST

O-linked attachment directly through S to T

Question 24

2 types of glycosylation

Answer 24

N-linked NX/ST

O-linked attachment directly through S to T

Question 25

hydroxylation

Answer 25

of proline and lysine
essential to collagen 
vitamin C ( humans have lost the last enzyme with ascorbic pathways so wee can't produce are vitamin C )  required for hydroxylation 
defiance can lead to scurvy 
diet

Question 26

folding and disease

Answer 26

structure defines function so function depends on structure

cells have developed extensive mechanism to prevent or remove misfloded proteins

Question 27

folding quuality

Answer 27

exposure of hydrophobic residues to the environment

Question 28

folding quality

Answer 28

exposure of hydrophobic residues to the environment

Question 29

PMD’s characteristics

Answer 29

result from misfolding
and aggregation of cellular prion protein
can be genetic or acquired
activation of an immune response causing inflammation as an early sign of disease

Question 30

best characterised PMD: the prion

Answer 30

result from misfolding
and aggregation of cellular prion protein
can be genetic or acquired
activation of an immune response causing inflammation as an early sign of disease

Question 31

prion

Answer 31

adopt a number of forms:
large, insoluble fibrillary aggregates (PrPSc) - Small, soluble, protease sensitive oligomers
- Higher activity relative to weight

Question 32

iatrogenic transmission

Answer 32

A current issue involves the spread of prions during medical intervention

Conventional methods of sterilisation of medical equipment are insensitive….
- contamination at the top involved sterilisation of electrode involving benzene, 70 % ethanol and formaldehyde vapour…