Which of the following are caused by hydrolysis?
Which of the following are caused by Radical Oxygen Species?
Bulky alkylation damage
What causes Alkylation Damage?
Radical oxygen species
Interacts with 6th O on guanine
Interacts with 3rd O on guanine
Methylation of guanine results in unstable base pairing
Over two cycles of replication, a methylated C-G will be replaced with an?
What protein catalyses Direct Reversal of Guanine methylation?
The enzyme involved in direct reversal catalyses the transfer of CH3 to the enzyme, killing it
How does the Direct Reversal enzyme 'flip out' the damaged guanine?
A helix-helix motif
A helix-turn-helix motif
A sheet-turn-sheet motif
The enzyme for direct reversal is not specific and so works globally
What is the reading head of the Direct Reversal enzyme made of?
Ala & Gly
Ser & Val
Tyr & Ser
The enzyme binds to the major groove using an HTH motif
Which happens first in the CH3 transfer?
Lys pushes H onto Tyr
Lys pushes CH3 onto Tyr
Tyr pushes H onto Lys
The new H+ pushes e-....
Onto O bound to CH3
Onto Lys bound to CH3
The e- added to the O pushes the CH3 onto the Lysine
Which of the following recognises the widowed G and fills the gap?
Arg on the head of the reading head
Lys on the head of the reading head
Val on the head of the reading head
UV irradiation of _ causes _?
Opens a 5-6 bond
Opens a 3-4 bond
Opens a 4-6 bond
A phosphobutane photo-dimer is formed
Why is UV radiation dangerous?
It alters DNA conformation
So helicases make mistakes
Bases are deleted
Bases are duplicated
How do 6-4 lesions form?
An O is transfered from on thymine to another
An N is transfered from on thymine to another
A C is transfered from on thymine to another
Damage is recognised by bases
How does photolyase work on 6-4 bonds?
Uses light to reverse the reaction
Uses UV to reverse the reaction
Binds to DNA and excises damaged bases
A 'protein wedge' forces DNA apart so it can work
An e- from diazaflavin is removed by UV and is passed onto what?
The electron will hopefully break the distorted bonds
The photolyase process can only work once
Which residues bind to the phosphate backbone in photolyase?
What does the widowed base pair bind to?