{"doi":"10.1093/toxsci/3.1.16","title":"Kinetic Analyses of the Microsomal Biotransformation of the Phosphorothioate Insecticides Chlorpyrifos and Parathion","abstract":null,"journal":"Toxicological Sciences","year":1983,"id":684665,"datarank":0.29188652235829704,"base_score":1.9459101490553132,"endowment":1.9459101490553132,"self_citation_contribution":0.29188652235829704,"citation_network_contribution":0.0,"self_endowment_contribution":0.29188652235829704,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":6,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"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":1788689,"name":"SHELDON D. MURPHY","orcid":null,"position":1,"is_corresponding":false},{"id":1788688,"name":"LESTER G. SULTATOS","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"resolved":true,"title":"Kinetic Analyses of the Microsomal Biotransformation of the Phosphorothioate Insecticides Chlorpyrifos and Parathion","abstract":"Kinetic Analyses of the Microsomal Biotransformation of the Phosphorothioate Insecticides Chlorphyrifos and Parathion. Sultatos, L.G. and Murphy, S.D. (1983). Fundam. and Appl. Toxicol. 3:16-21. Chlorpyrifos [0,0-diethyl-0-(3,5,6-trichloro-2-pyridyl) phosphorothioate] was metabolized to chlorpyrifos oxon [0,0-diethyl-0-(3,5,6-trichloro-2-pyridyl) phosphate] and to 3,5,6-trichloro-2-pyridinol by mouse hepatic microsomes. Formation of both chlorpyrifos oxon and 3,5,6-trichloro-2-pyridinol required NADPH, and was inhibited by carbon monoxide. Kinetic analyses using direct linear plots determined the appKm's for formation of chlorpyrifos oxon and 3,5,6-trichloro-2-pyridinol to be 20.9 ± 3.3 μM and 16.1 ± 3.4 μM respectively, while the appVmax's for the same reactions were 3.9 ± 0.2 nmols/100 mg liver/min and 8.1 ± 0.3 nmols/100 mg liver/min respectively. Incubation of parathion [0,0-diethyl-0-(4-nitrophenyl) phosphorothioate] with mouse hepatic microsomes produced paraoxon [0,0-diethyl-0-(4-nitrophenyl) phosphate] and p-nitrophenol. The appKm's for the formation of paraoxon and p-nitrophenol were 29.6 ± 4.2 μM and 26.5 ± 3.8 μM respectively, with appVmax's of 5.8 ± 0.6 nmols/100 mg liver/min and 6.7 ± 0.5 nmols/100 mg liver/min, respectively. Incubation of both parathion and chlorpyrifos at various concentrations with mouse hepatic microsomes resulted in inhibition of production of paraoxon, p-nitrophenol, chlorpyrifos oxon, and 3,5,6-trichloro-2-pyridinol, which was characteristic of mixed type inhibition. This complex kinetic behavior could arise as a result of competitive interactions of parathion and chlorpyrifos with multiple forms of microsomal cytochrome P-450.","is_dataset_classified":null,"base_score":1.9459101490553132,"endowment":1.9459101490553132,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"26207759","pmcid":null,"openalex_id":"https://openalex.org/W4254400135","authors":[],"funders":[],"total_grants":0,"fwci":0.0,"citation_percentile":0.5042166,"influential_citations":0,"citation_trend":[{"year":2013,"count":1},{"year":2022,"count":1}],"oa_status":"closed","license":null,"oa_locations":[{"url":"http://academic.oup.com/toxsci/article-pdf/3/1/16/4591846/3-1-16.pdf","host_type":"publisher"},{"url":"https://doi.org/10.1093/toxsci/3.1.16","host_type":"journal"}],"fields_of_study":["Pesticide and Herbicide Environmental Studies","Pesticide Exposure and Toxicity","Environmental Toxicology and Ecotoxicology"],"mesh_terms":[],"keywords":["Oxon","Paraoxon","Microsome","Parathion","Chlorpyrifos","Chemistry","Incubation","Biotransformation","Microsoma","Organophosphate","Metabolite","Pesticide","Chromatography","Biochemistry","Toxicology","Enzyme","Acetylcholinesterase","Biology"],"sdg_mappings":[{"sdg_number":0,"sdg_label":"Clean water and sanitation"}],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-08-18T14:42:11.293533Z","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":[]}