Mthf transfers this photoexcitation to fadh 3 fadh

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Unformatted text preview: uclease 2. MTHF transfers this photoexcitation to FADH 3. FADH transfers an electron to the dimer, breaking the dimer into thymine monomers, then takes the electron back. Note the baseipping mechanism of the enzyme! MHTF = methenyltetrahydrofolate Unfortunately, we (humans) don’t have photolyase! PDB # 1TEZ 7 8 Nucleotide excision repair DNA mismatch repair (in E. coli; humans lack MutH) Xeroderma pigmentosum - genetic diseases of excision repair. In humans NER utilizes 16 di erent proteins. Mutations in many of these cause XP. = ABC excinuclease Xeroderma pigmentosum (XP) is characterized by sun sensitivity (severe sunburn with blistering, persistent erythema on minimal sun exposure, marked freckle-like pigmentation of the face before age two years), ocular involvement (photophobia, keratitis, atrophy of the skin of the lids), and a greatly increased risk of cutaneous neoplasms (basal cell carcinoma, squamous cell carcinoma, melanoma). Approximately 25% of a ected individuals have neurologic manifestations (acquired microcephaly, diminished or absent deep tendon stretch re exes, progressive sensorineural hearing loss, and progressive cognitive impairme...
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