{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,4]],"date-time":"2026-05-04T04:27:10Z","timestamp":1777868830407,"version":"3.51.4"},"reference-count":0,"publisher":"S. Karger AG","license":[{"start":{"date-parts":[[2017,8,11]],"date-time":"2017-08-11T00:00:00Z","timestamp":1502409600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"},{"start":{"date-parts":[[2017,8,11]],"date-time":"2017-08-11T00:00:00Z","timestamp":1502409600000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Enzyme"],"abstract":"<jats:p>In the presence of saturating concentrations of adenosine triphosphate (ATP)\nand rate-limiting amounts of pyridoxal, theophylline was found to inhibit sheep brain pyridoxal\nkinase (EC 2.7.1.35) competitively. The apparent inhibition constant (K(i)) of theophylline\nfor pyridoxal kinase was determined as 8.7 \u03bcmol\/l. Theophylline concentrations of up\nto 60 \u03bcmol\/1 did not affect pyridoxal phosphorylation in the presence of saturating amounts\nof pyridoxal and rate-limiting concentrations of ATP. Caffeine was less potent to inhibit\npyridoxal kinase (K(i) = 45 \u03bcmol\/l) due to the presence of a methyl group on the 7 position of\nthe xanthine ring structure. Theobromine showed only a weak inhibition of pyridoxal kinase\n(K(i) = 453 \u03bcmol\/l). The presence of a hydroxyethyl, hydroxypropyl or dihydroxypropyl group\non the N7 position of theophylline completely abolished inhibition of pyridoxal kinase.\nEnprofylline (3-propylxanthine), a recently described bronchodilator, was also able to inhibit\npyridoxal kinase with a K, of 256 \u03bcmol\/l.<\/jats:p>","DOI":"10.1159\/000468709","type":"journal-article","created":{"date-parts":[[2017,8,11]],"date-time":"2017-08-11T17:21:16Z","timestamp":1502472076000},"page":"72-79","source":"Crossref","is-referenced-by-count":19,"title":["Inhibition of Pyridoxal Kinase by Methylxanthines"],"prefix":"10.1159","author":[{"given":"Johan B.","family":"Ubbink","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Siegbert","family":"Bissbort","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Vermaak","family":"Hayward","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Rhena","family":"Delport","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"127","published-online":{"date-parts":[[2017,8,11]]},"container-title":["Enzyme"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/karger.com\/article-pdf\/doi\/10.1159\/000468709","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,30]],"date-time":"2026-04-30T12:45:09Z","timestamp":1777553109000},"score":1,"resource":{"primary":{"URL":"https:\/\/karger.com\/article\/doi\/10.1159\/000468709"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2017,8,11]]},"references-count":0,"URL":"https:\/\/doi.org\/10.1159\/000468709","archive":["Portico"],"relation":{},"ISSN":["0013-9432","2504-2564"],"issn-type":[{"value":"0013-9432","type":"print"},{"value":"2504-2564","type":"electronic"}],"subject":[],"published":{"date-parts":[[2017,8,11]]}}}