{"doi":"10.1101/2023.08.22.554361","title":"Cucurbit[7]uril Enhances Distance Measurements of Spin-Labeled Proteins","abstract":"ABSTRACT We report complex formation between the chloroacetamide 2,6-diazaadamantane nitroxide radical (ClA-DZD) and cucurbit[7]uril (CB-7), for which the association constant in water, K a = 1.9 × 10 6 M -1 , is at least one order of magnitude higher than the previously studied organic radicals. The radical is highly immobilized by CB-7, as indicated by the increase of the rotational correlation time, τ rot , by a factor of 36, relative to that in the buffer solution. The X-ray structure of ClA-DZD@CB-7 shows the encapsulated DZD guest inside the undistorted CB-7 host, with the pendant group protruding outside. Upon addition of CB-7 to T4 Lysozyme (T4L) doubly spin-labeled with the iodoacetamide derivative of DZD, we observe the increase in τ rot and electron spin coherence time, T m , along with the narrowing of inter-spin distance distributions. Sensitivity of the DEER measurements at 83 K increases by a factor 4 – 9, compared to the common spin label such as MTSL, which is not affected by CB-7. Inter-spin distances of 3-nm could be reliably measured in water/glycerol up to temperatures near the glass transition/melting temperature of the matrix at 200 K, thus bringing us closer to the goal of supramolecular recognition-enabled long-distance DEER measurements at near physiological temperatures. The X-ray structure of DZD-T4L 65 at 1.12 Å resolution allows for unambiguous modeling of the DZD label (0.88 occupancy), indicating undisturbed structure and conformation of the protein. Abstract Figure","journal":"bioRxiv (Cold Spring Harbor Laboratory)","year":2023,"id":400517,"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":1,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9542,"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":298191,"name":"Richard A. Stein","orcid":"0000-0002-0541-7150","position":1,"is_corresponding":false},{"id":588281,"name":"Maren Pink","orcid":"0000-0001-9049-4574","position":2,"is_corresponding":false},{"id":1097507,"name":"Peter Madzelan","orcid":null,"position":3,"is_corresponding":false},{"id":763472,"name":"Thacien Ngendahimana","orcid":"0000-0002-2646-7114","position":4,"is_corresponding":false},{"id":763473,"name":"Suchada Rajca","orcid":"0000-0003-0904-8329","position":5,"is_corresponding":false},{"id":388663,"name":"Mark A. Wilson","orcid":"0000-0001-6317-900X","position":6,"is_corresponding":false},{"id":375077,"name":"Sandra S. Eaton","orcid":null,"position":7,"is_corresponding":false},{"id":373416,"name":"Gareth R. Eaton","orcid":"0000-0001-7429-8469","position":8,"is_corresponding":false},{"id":298192,"name":"Hassane S. Mchaourab","orcid":"0000-0002-5673-0980","position":9,"is_corresponding":false},{"id":480958,"name":"Andrzej Rajca","orcid":"0000-0002-8856-1536","position":10,"is_corresponding":false},{"id":1080313,"name":"Zhimin Yang⌈","orcid":null,"position":0,"is_corresponding":true}],"reference_count":86,"raw_metadata":null,"created_at":"2026-07-19T01:20:04.010538Z","pmid":"37662277","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":[]}