What is the function of N5,N10-methylene tetrahydrofolate in the enzyme DNA Photolyase?
A) It catalyzes the transfer of a hydroxyethyl group to DNA
B) It catalyzes the transfer of a methyl group to DNA
C) It catalyzes electron-transfer to FAD
D) It catalyzes energy-transfer to FAD
E) It catalyzes energy-transfer to pyrimidine dimers
Answer. (E)
Pyrimidine dimers are formed due to exposure to UV light between the adjacent pyrimidines.
DNA photolyase are 55-65 KDa enzymes which catalyze the breakdown of these dimers which may pose a problem and may lead to frameshift or halting of replication or transcription. This may lead to cell death.
Its substrate speciifcity is due to recognition of the phosphodiester backbone and not by sequence specificty.
It involves the use of 2 cofactors that act as a chromophore -
FADH2
N5, N10- Methylene THF
N5, N10- Methylene THF absorbs a photon of light and transfers it to FADH2 via dipole-dipole intercations. FADH2 further transfers the enrgy to the pyrimidine dimer and so leads to its breakdown.
Get Answers For Free
Most questions answered within 1 hours.