Topic 3 (proteins recap) Flashcards
What is the proteome
Full set of proteins encoded by human genome
What is disrupted in phyenylketonuria?
Phenylalanine hydroxylase
What happens in phyenylketonuria
No breakdown of AA pheynlalanine
Permanent brain damage
What is missing in haemophilia
Factor 8
Duchenne muscular dystropy is caused by what?
Dystrophin muscle protein absent/ineffective
Collagen mutation can lead to what?
Osteogenesis imperfecta
What causes scurvy
Lack of vit c leads to lack of collagen production
Why is vit.c associated with scurvy?
Vitamin C is cofactor for hydroxylases during collagen synthesis
Myasthenia gravis is caused by what?
Antibody to neurotransmitter receptor
Name the 9 non polar AA
Glycine, Alanine, Valine, Leucine, Isoleucine, Methionine, Phenylalanine, Tryptophan, proline
GAVLIMFWP
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Name the 6 polar AA
Serine, Threonine, Cysteine, Asparagine, Glutamine, Tyrosine
STCNQY
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Name the 2 acidic AA
Aspartic Acid, Glutamic Acid
Name the 3 basic AA
Lysine, Arginine, Histidine
All amino acids are what except glycine?
Why?
all AA are chiral
Glycine only has Hydro as R group
Which isomer is found in proteins?
L amino acids
pka of Carboxylic groups
1.8-2.5
pka of A-amino groups
9-10
pka of histidine
6
definition of pka
pH where 50% of group is ionised
typical proteins have how many AA
50-2000
What reaction forms a peptide bond?
Condensation reaction
Why is trans peptide bond common
Most advantageous due to Oxy and Hydr on opposite side of bond
H bonds occur between that two types of bonds ion A helix every …. residues
N-H
C=O
4 residues
Does alpha contain interchain bonds?
no only B sheets have intrachain and interchain
R group is found on what part of a B sheet
Outside plane of sheet
What type of amino acids are Hydrophobic?
Where are they found in a protein
Non-Polar
Interior of soluble protein
What type of bonds are present in Quaternary / tertiary bonding to stabilise structures
Disulphide covalent
Non covalent (Van der Waals/Hbonds)
What type of reaciton forms disulphide bonds
Oxidation reaction
between pair of cysteine = cystine
How are salt bridges formed?
Oppositely charged side chains
How do Dipoles form?
2 atoms of opposing charge share electrons, however electrons tend to lean to one atom more than another leading to unequal sharing
With dipoles and Van Der Waals, what occurs?
temporary / induced dipoles are being constantly produced
What type of AA can H-bond
Polar residues
What do chaperones do?
Bind to short segments of protein
Facilitates correct folding
What do chaperonins do?
Form folding chambers
Providing stable environment for correct folding
Prevents aggregation
Loss of neurons in what part of the brain occur in alzheimer’s
cerebral cortex
What aggregates in Alzheimers?
Insoluble fibres of Amyloid B protein = plaque
Creutzfeldt jacob disease leads to what 3 things
memory loss
loss of co-ordination
coma
What causes CJD
Prion Protein
PrP^sc
If abnormal PrP^sc forms with a helical PrP^sc, what occurs
Insoluble aggregates form
BSE is caused by what?
Infectious protein agent
