{"doi":"10.3390/molecules28031133","title":"Structural and Mechanistic Basis for the Inactivation of Human Ornithine Aminotransferase by (3S,4S)-3-Amino-4-fluorocyclopentenecarboxylic Acid","abstract":"Ornithine aminotransferase (OAT) is overexpressed in hepatocellular carcinoma (HCC), and we previously showed that inactivation of OAT inhibits the growth of HCC. Recently, we found that (3S,4S)-3-amino-4-fluorocyclopentenecarboxylic acid (5) was a potent inactivator of γ-aminobutyric acid aminotransferase (GABA-AT), proceeding by an enamine mechanism. Here we describe our investigations into the activity and mechanism of 5 as an inactivator of human OAT. We have found that 5 exhibits 10-fold less inactivation efficiency (kinact/KI) against hOAT than GABA-AT. A comprehensive mechanistic study was carried out to understand its inactivation mechanism with hOAT. pKa and electrostatic potential calculations were performed to further support the notion that the α,β-unsaturated alkene of 5 is critical for enhancing acidity and nucleophilicity of the corresponding intermediates and ultimately responsible for the improved inactivation efficiency of 5 over the corresponding saturated analogue (4). Intact protein mass spectrometry and the crystal structure complex with hOAT provide evidence to conclude that 5 mainly inactivates hOAT through noncovalent interactions, and that, unlike with GABA-AT, covalent binding with hOAT is a minor component of the total inhibition which is unique relative to other monofluoro-substituted derivatives. Furthermore, based on the results of transient-state measurements and free energy calculations, it is suggested that the α,β-unsaturated carboxylate group of PLP-bound 5 may be directly involved in the inactivation cascade by forming an enolate intermediate. Overall, compound 5 exhibits unusual structural conversions which are catalyzed by specific residues within hOAT, ultimately leading to an enamine mechanism-based inactivation of hOAT through noncovalent interactions and covalent modification.","journal":"Molecules","year":2023,"id":387760,"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":0.9535,"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":731998,"name":"Arseniy Butrin","orcid":null,"position":1,"is_corresponding":false},{"id":1156817,"name":"Brett A. Beaupre","orcid":"0000-0002-2893-7837","position":2,"is_corresponding":false},{"id":326451,"name":"Gláucio Monteiro Ferreira","orcid":"0000-0002-1952-9428","position":3,"is_corresponding":false},{"id":425915,"name":"Peter F. Doubleday","orcid":"0000-0002-1784-1282","position":4,"is_corresponding":false},{"id":1156818,"name":"Daniel Grass","orcid":"0000-0002-5011-4108","position":5,"is_corresponding":false},{"id":425917,"name":"Wei Zhu","orcid":"0000-0003-0197-9911","position":6,"is_corresponding":false},{"id":237416,"name":"Neil L. Kelleher","orcid":"0000-0002-8815-3372","position":7,"is_corresponding":false},{"id":949263,"name":"Graham R. Moran","orcid":"0000-0002-6807-1302","position":8,"is_corresponding":false},{"id":531884,"name":"Dali Liu","orcid":"0000-0002-7587-703X","position":9,"is_corresponding":false},{"id":425918,"name":"Richard B. Silverman","orcid":"0000-0001-9034-1084","position":10,"is_corresponding":false},{"id":318195,"name":"Sida Shen","orcid":"0000-0002-0295-2545","position":0,"is_corresponding":true}],"reference_count":45,"raw_metadata":null,"created_at":"2026-07-19T01:18:08.845494Z","pmid":"36770800","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":[]}