{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,7]],"date-time":"2026-02-07T23:59:06Z","timestamp":1770508746054,"version":"3.49.0"},"reference-count":0,"publisher":"Canadian Science Publishing","issue":"10","license":[{"start":{"date-parts":[[1970,10,1]],"date-time":"1970-10-01T00:00:00Z","timestamp":23587200000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/www.nrcresearchpress.com\/page\/about\/CorporateTextAndDataMining"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Can. J. Biochem."],"published-print":{"date-parts":[[1970,10,1]]},"abstract":"<jats:p> Some properties of phosphodiesterase I from microsomes of rat intestinal mucosa were studied using the p-nitrophenyl ester of thymidine 5\u2032-phosphate as substrate. The optimum pH was found to be 9.5\u20139.6 in several buffer systems. The activity was destroyed at temperatures of 63\u201368\u00b0, depending on the pH of the medium. Mg<jats:sup>2+<\/jats:sup>, Ca<jats:sup>2+<\/jats:sup>, Sr<jats:sup>2+<\/jats:sup>, Ba<jats:sup>2+<\/jats:sup>, and Ni<jats:sup>2+<\/jats:sup> had a variable activating effect while Al<jats:sup>3+<\/jats:sup>, Cu<jats:sup>2+<\/jats:sup>, and Be were inhibitory. The enzyme was inhibited completely by 10<jats:sup>\u22125<\/jats:sup>\u2002M EDTA or EGTA in the assay system used. The evidence obtained suggested phosphodiesterase I is a metal-requiring enzyme. Glycine, bicine, and tricine inhibited the enzyme at higher concentrations. Cysteine, 2-mercaptoethanol, and dithiothreitol were strongly inhibitory at a concentration of 10<jats:sup>\u22123<\/jats:sup>\u2002M. The K<jats:sub>m<\/jats:sub> of the enzyme was 8.5\u2002\u00d7\u200210<jats:sup>\u22124<\/jats:sup>\u2002M. In 6\u2002M urea 40% of the activity of the enzyme was lost irreversibly after 24\u2002h at 4\u00b0. In 3\u2002M urea there was an immediate and reversible mixed competitive\u2013noncompetitive inhibition and the K<jats:sub>m<\/jats:sub> was increased seven to eight times. <\/jats:p>","DOI":"10.1139\/o70-179","type":"journal-article","created":{"date-parts":[[2009,12,17]],"date-time":"2009-12-17T17:12:30Z","timestamp":1261069950000},"page":"1151-1159","source":"Crossref","is-referenced-by-count":7,"title":["Some properties of phosphodiesterase I from microsomes of rat intestinal mucosa"],"prefix":"10.1139","volume":"48","author":[{"given":"I.","family":"Hynie","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"S. H.","family":"Zbarsky","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"155","container-title":["Canadian Journal of Biochemistry"],"original-title":[],"language":"en","link":[{"URL":"http:\/\/www.nrcresearchpress.com\/doi\/pdf\/10.1139\/o70-179","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2020,1,5]],"date-time":"2020-01-05T19:06:42Z","timestamp":1578251202000},"score":1,"resource":{"primary":{"URL":"http:\/\/www.nrcresearchpress.com\/doi\/10.1139\/o70-179"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1970,10,1]]},"references-count":0,"journal-issue":{"issue":"10","published-print":{"date-parts":[[1970,10,1]]}},"alternative-id":["10.1139\/o70-179"],"URL":"https:\/\/doi.org\/10.1139\/o70-179","relation":{},"ISSN":["0008-4018"],"issn-type":[{"value":"0008-4018","type":"print"}],"subject":[],"published":{"date-parts":[[1970,10,1]]}}}