{"doi":"10.1002/cbic.202300347","title":"A Fluorescence‐Based Assay for <i>N</i><sup>5</sup>‐Carboxyaminoimidazole Ribonucleotide Mutase","abstract":"Abstract The enzyme N 5 ‐carboxylaminoinidazole ribonucleotide (N 5 ‐CAIR) mutase is found in microbial de novo purine biosynthesis but is absent in humans making it an attractive antimicrobial target. N 5 ‐CAIR mutase catalyzes the synthesis of carboxyaminoimidazole ribonucleotide (CAIR) from N 5 ‐CAIR which is itself prepared from aminoimidazole ribonucleotide (AIR) by the enzyme N 5 ‐CAIR synthetase. During our research on identifying inhibitors of N 5 ‐CAIR mutase, we developed an innovative, fluorescence‐based assay to measure the activity of this enzyme. This assay relies upon our recent serendipitous observation that AIR reversibly reacts with the compound isatin. Reaction of a fluorescently‐tagged isatin with AIR resulted in a large increase in fluorescence intensity allowing a measurement of the concentration of AIR in solution. From this observation, we developed a reproducible, non‐continuous assay that can replicate the known kinetic parameters of the enzyme and can readily detect a recognized inhibitor of the enzyme. This assay should find utility in screening for inhibitors targeting N 5 ‐CAIR mutase.","journal":"ChemBioChem","year":2023,"id":383504,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":2,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9659,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2023-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":768876,"name":"Shiv K. Sharma","orcid":"0000-0001-5249-4741","position":1,"is_corresponding":false},{"id":1150979,"name":"Cale C. Streeter","orcid":null,"position":2,"is_corresponding":false},{"id":768877,"name":"Steven M. Firestine","orcid":"0000-0001-7325-8043","position":3,"is_corresponding":false},{"id":1150597,"name":"Marcella F. Sharma","orcid":"0000-0002-6400-2107","position":0,"is_corresponding":true}],"reference_count":26,"raw_metadata":null,"created_at":"2026-07-19T01:17:29.050285Z","pmid":"37474455","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":[]}