{"doi":"10.1111/php.12183","title":"On the Formation of Thymine Photodimers in Thymine Single Strands and Calf Thymus <scp>DNA</scp>","abstract":"<jats:title>Abstract</jats:title><jats:p>Solar light leads to thymine dimers that are mutagenic and primary cause of skin cancer. Here, we report absorption and synchrotron radiation circular dichroism (<jats:styled-content style=\"fixed-case\">CD</jats:styled-content>) spectra of T<jats:sub><jats:italic>n</jats:italic></jats:sub> single strands with different number <jats:italic>n</jats:italic> of bases (<jats:italic>n </jats:italic>=<jats:italic> </jats:italic>2–7, 10, 11) recorded after various 254 nm irradiation times. From a principal component analysis of the <jats:styled-content style=\"fixed-case\">CD</jats:styled-content> spectra, we extract fingerprint spectra of both the cyclobutane pyrimidine dimer (<jats:styled-content style=\"fixed-case\">CPD</jats:styled-content>) and the pyrimidine (6‐4) pyrimidone photoadduct (64PP). Extending the <jats:styled-content style=\"fixed-case\">CD</jats:styled-content> measurements to the vacuum ultraviolet region in combination with systematic examinations of size effects is a new approach to gain insight on the dimeric photoproducts. We find a simple linear correlation between <jats:italic>n</jats:italic> and average number of dimers formed after 1 h of irradiation. The probability for a thymine to engage in a dimer increases from 32% for <jats:italic>n </jats:italic>=<jats:italic> </jats:italic>2 to 41% for <jats:italic>n </jats:italic>=<jats:italic> </jats:italic>11, which implies limited effects of terminal thymines, <jats:italic>i.e</jats:italic>., the reaction does not occur preferentially at the extremities of the single strands as previously stated. It is even possible to form two dimers with only two bridging thymines. Finally, experiments conducted on calf thymus <jats:styled-content style=\"fixed-case\">DNA</jats:styled-content> provided a similar signature of the photodimer, but differences are also evident.</jats:p>","journal":"Photochemistry and Photobiology","year":2014,"id":37380,"datarank":0.7434593275657266,"base_score":2.4849066497880004,"endowment":2.4849066497880004,"self_citation_contribution":0.37273599746820013,"citation_network_contribution":0.37072333009752645,"self_endowment_contribution":0.37273599746820013,"citer_contribution":0.37072333009752645,"corpus_percentile":null,"corpus_rank":null,"citation_count":11,"citer_count":7,"citers_with_citation_signal":7,"citers_with_endowment":7,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":187448,"name":"Søren Vrønning Hoffmann","orcid":null,"position":1,"is_corresponding":false},{"id":187449,"name":"Steen Brøndsted Nielsen","orcid":null,"position":2,"is_corresponding":false},{"id":187447,"name":"Lisbeth Munksgaard Baggesen","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"base_score":2.4849066497880004,"endowment":2.4849066497880004,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"24117460","pmcid":null,"openalex_id":"https://openalex.org/W2105070652","authors":[],"funders":[],"total_grants":0,"fwci":0.2991,"citation_percentile":0.62754169,"influential_citations":0,"citation_trend":[{"year":2014,"count":1},{"year":2016,"count":1},{"year":2018,"count":2},{"year":2019,"count":1},{"year":2020,"count":1},{"year":2021,"count":1},{"year":2022,"count":2},{"year":2025,"count":2}],"oa_status":"closed","license":"http://onlinelibrary.wiley.com/termsAndConditions#vor","oa_locations":[{"url":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fphp.12183","host_type":"publisher"},{"url":"https://onlinelibrary.wiley.com/doi/pdf/10.1111/php.12183","host_type":"publisher"},{"url":"https://doi.org/10.1111/php.12183","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/24117460","host_type":"repository"},{"url":"https://pure.au.dk/portal/en/publications/1d3b04ed-2d78-4d5d-8a7f-f304cecf8723","host_type":""}],"fields_of_study":["DNA and Nucleic Acid Chemistry","Optical Coatings and Gratings","Metamaterials and Metasurfaces Applications","Medicine","Chemistry","Animals","Cattle","Circular Dichroism","DNA","Light","Molecular Structure","Pyrimidine Dimers","Thymine"],"mesh_terms":["Animals","Cattle","Circular Dichroism","DNA","Light","Pyrimidine Dimers","Thymine","Molecular Structure"],"keywords":["Thymine","DNA","Chemistry","Stereochemistry","Biochemistry"],"sdg_mappings":[],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-06-10T19:19:58.203658Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}