{"doi":"10.1093/clinchem/31.1.14","title":"Optimized conditions for determining activity concentration of alpha-amylase in serum, with 1,4-alpha-D-4-nitrophenylmaltoheptaoside as substrate.","abstract":"<jats:title>Abstract</jats:title>\n               <jats:p>We describe a method for measuring the catalytic activity of alpha-amylase (EC 3.2.1.1) in serum and urine, by use of a defined substrate: 1,4-alpha, D-4-nitrophenyl maltoheptaoside. We use a phosphate buffer of pH 7.10, containing chloride as activator and alpha-glucosidase (EC 3.2.1.20) as the auxiliary enzyme. After a lag phase of 4 min at 25 degrees C or 30 degrees C, or 3 min at 37 degrees C, the increase of absorption of 4-nitrophenol is measured at 410 nm or 405 nm. The pH value of the assay mixture is a compromise between optimum pH for the alpha-amylase reaction, shortest possible lag phase, and an acceptable absorptivity of 4-nitrophenol. Because the dissociation of 4-nitrophenol depends strongly on pH and temperature, we determined its absorptivity with various combinations of these variables in the assay. Heparin-treated plasma can be used, but not EDTA, fluoride, or citrate. Lipemia, hemoglobin less than or equal to mumol/L, bilirubin less than or equal to 170 mumol/L, glucose less than or equal to 100 mmol/L, and ascorbic acid less than or equal to 1 mmol/L of sample do not interfere in the assay.</jats:p>","journal":"Clinical Chemistry","year":1985,"id":657559,"datarank":8.609720307074747,"base_score":4.394449154672439,"endowment":4.394449154672439,"self_citation_contribution":0.6591673732008659,"citation_network_contribution":7.9505529338738805,"self_endowment_contribution":0.6591673732008659,"citer_contribution":7.9505529338738805,"corpus_percentile":null,"corpus_rank":null,"citation_count":80,"citer_count":78,"citers_with_citation_signal":73,"citers_with_endowment":73,"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":1716536,"name":"U Neumann","orcid":null,"position":1,"is_corresponding":false},{"id":1716537,"name":"E Schaich","orcid":null,"position":2,"is_corresponding":false},{"id":1716538,"name":"S von Bülow","orcid":null,"position":3,"is_corresponding":false},{"id":1716539,"name":"A W Wahlefeld","orcid":null,"position":4,"is_corresponding":false},{"id":1716535,"name":"E Rauscher","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"resolved":true,"title":"Optimized conditions for determining activity concentration of alpha-amylase in serum, with 1,4-alpha-D-4-nitrophenylmaltoheptaoside as substrate.","abstract":"<jats:title>Abstract</jats:title>\n               <jats:p>We describe a method for measuring the catalytic activity of alpha-amylase (EC 3.2.1.1) in serum and urine, by use of a defined substrate: 1,4-alpha, D-4-nitrophenyl maltoheptaoside. We use a phosphate buffer of pH 7.10, containing chloride as activator and alpha-glucosidase (EC 3.2.1.20) as the auxiliary enzyme. After a lag phase of 4 min at 25 degrees C or 30 degrees C, or 3 min at 37 degrees C, the increase of absorption of 4-nitrophenol is measured at 410 nm or 405 nm. The pH value of the assay mixture is a compromise between optimum pH for the alpha-amylase reaction, shortest possible lag phase, and an acceptable absorptivity of 4-nitrophenol. Because the dissociation of 4-nitrophenol depends strongly on pH and temperature, we determined its absorptivity with various combinations of these variables in the assay. Heparin-treated plasma can be used, but not EDTA, fluoride, or citrate. Lipemia, hemoglobin less than or equal to mumol/L, bilirubin less than or equal to 170 mumol/L, glucose less than or equal to 100 mmol/L, and ascorbic acid less than or equal to 1 mmol/L of sample do not interfere in the assay.</jats:p>","is_dataset_classified":null,"base_score":4.394449154672439,"endowment":4.394449154672439,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"3871178","pmcid":null,"openalex_id":"https://openalex.org/W1862308705","authors":[],"funders":[],"total_grants":0,"fwci":1.5486,"citation_percentile":0.81672297,"influential_citations":0,"citation_trend":[{"year":2012,"count":1},{"year":2014,"count":3},{"year":2015,"count":1},{"year":2016,"count":1},{"year":2017,"count":2},{"year":2018,"count":2},{"year":2019,"count":1},{"year":2023,"count":1}],"oa_status":"bronze","license":"https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model","oa_locations":[{"url":"https://academic.oup.com/clinchem/article-pdf/31/1/14/31820001/clinchem0014.pdf","host_type":"journal"},{"url":"https://academic.oup.com/clinchem/article-pdf/31/1/14/31820001/clinchem0014.pdf","host_type":"publisher"},{"url":"http://academic.oup.com/clinchem/article-pdf/31/1/14/32770452/clinchem0014.pdf","host_type":"publisher"},{"url":"https://doi.org/10.1093/clinchem/31.1.14","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/3871178","host_type":"repository"}],"fields_of_study":["Enzyme Production and Characterization"],"mesh_terms":["alpha-Amylases","Buffers","Evaluation Studies as Topic","Glucosides","Glycosides","Humans","Hydrogen-Ion Concentration","Isoenzymes","Pancreas","Saliva","Spectrophotometry","Substrate Specificity","Temperature","Time Factors"],"keywords":["Alpha (finance)","Alpha-amylase","Substrate (aquarium)","Chemistry","Chromatography","Biochemistry","Amylase","Biology","Medicine","Enzyme","Surgery","Ecology"],"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":"2026-08-12T01:33:23.739425Z","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":[]}