{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,18]],"date-time":"2025-10-18T10:25:40Z","timestamp":1760783140617,"version":"build-2065373602"},"reference-count":21,"publisher":"Wiley","issue":"5","license":[{"start":{"date-parts":[[2009,5,5]],"date-time":"2009-05-05T00:00:00Z","timestamp":1241481600000},"content-version":"vor","delay-in-days":4,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biotechnology Journal"],"published-print":{"date-parts":[[2009,5]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>The present work focuses on the development and basic characterization of a new magnetic biocatalyst, namely penicillin G acylase (PGA), immobilized in sol\u2010gel matrices with magnetic properties, ultimately aimed for application in cephalexin (CEX) synthesis. A mechanically stable carrier, based on porous xerogels silica matrixes starting from tetramethoxysilane (TMOS), was prepared leading to micro\u2010carriers with medium sized particles of 30 \u03bcm, as determined by scanning electron microscopy. An immobilization yield of 95\u2013100% and a recovered activity of 50\u201365% at 37\u00b0C, as determined by penicillin G (PG) hydrolysis (pH STAT method), were observed. These results clearly exceed those reported in a previous work on PGA immobilization in sol\u2010gel, where only 10% of activity was recovered. The values of activity were kept constant for 6 months. Immobilized PGA (682 U\/g<jats:sub>dry weight<\/jats:sub>) retained high specific activity throughout ten consecutive runs for PG hydrolysis, suggesting adequate biocatalyst stability. The CEX synthesis was performed at 14\u00b0C, using the free and immobilized PGA in aqueous medium. Phenylglycine methyl ester was used as acyl donor at 90 mM and 7\u2010aminodeacetoxycephalosporanic acid was the limiting substrate at 30 mM. The CEX stoichiometric yield after 1\u2010h reaction was close to 68% (23 mM CEX\/h) and 65% (19 mM CEX\/h), respectively.<\/jats:p>","DOI":"10.1002\/biot.200800287","type":"journal-article","created":{"date-parts":[[2009,5,5]],"date-time":"2009-05-05T08:13:33Z","timestamp":1241511213000},"page":"695-702","source":"Crossref","is-referenced-by-count":12,"title":["A new biocatalyst: Penicillin G acylase immobilized in sol\u2010gel micro\u2010particles with magnetic properties"],"prefix":"10.1002","volume":"4","author":[{"given":"Susana M. S. A.","family":"Bernardino","sequence":"first","affiliation":[]},{"given":"Pedro","family":"Fernandes","sequence":"additional","affiliation":[]},{"given":"Lu\u00eds P.","family":"Fonseca","sequence":"additional","affiliation":[]}],"member":"311","published-online":{"date-parts":[[2009,5,18]]},"reference":[{"key":"e_1_2_1_2_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.biotechadv.2005.05.003"},{"key":"e_1_2_1_3_2","doi-asserted-by":"publisher","DOI":"10.1002\/1615-4169(200108)343:6\/7<559::AID-ADSC559>3.0.CO;2-Z"},{"key":"e_1_2_1_4_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0141-0229(99)00153-2"},{"key":"e_1_2_1_5_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.tibtech.2006.12.005"},{"key":"e_1_2_1_6_2","doi-asserted-by":"publisher","DOI":"10.1021\/op9700643"},{"key":"e_1_2_1_7_2","doi-asserted-by":"publisher","DOI":"10.1002\/bit.20728"},{"key":"e_1_2_1_8_2","doi-asserted-by":"publisher","DOI":"10.1002\/adsc.200505042"},{"key":"e_1_2_1_9_2","doi-asserted-by":"publisher","DOI":"10.1039\/b512706h"},{"key":"e_1_2_1_10_2","doi-asserted-by":"publisher","DOI":"10.1021\/cm00046a008"},{"key":"e_1_2_1_11_2","doi-asserted-by":"publisher","DOI":"10.1002\/(SICI)1097-0290(19960305)49:5<527::AID-BIT5>3.0.CO;2-L"},{"key":"e_1_2_1_12_2","doi-asserted-by":"publisher","DOI":"10.1016\/S1381-1169(98)00043-0"},{"key":"e_1_2_1_13_2","doi-asserted-by":"publisher","DOI":"10.1023\/A:1015572020633"},{"key":"e_1_2_1_14_2","unstructured":"Brinker J. C. Scherer G. W. (Eds.) Sol\u2010Gel Science: the physics and chemistry of Sol\u2010Gel processing Book News Inc. Portland OR 1990."},{"key":"e_1_2_1_15_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0040-4039(00)01522-7"},{"key":"e_1_2_1_16_2","doi-asserted-by":"publisher","DOI":"10.1002\/bit.1066"},{"key":"e_1_2_1_17_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.jbiotec.2005.06.018"},{"key":"e_1_2_1_18_2","doi-asserted-by":"publisher","DOI":"10.6028\/jres.081A.011"},{"key":"e_1_2_1_19_2","doi-asserted-by":"publisher","DOI":"10.1002\/jctb.280580105"},{"key":"e_1_2_1_20_2","unstructured":"De Vroom E. Penicillin G acylase immobilized with a crosslinked mixture of gelled gelatin and amino polymer.US6060268 Patent2000."},{"key":"e_1_2_1_21_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.molcatb.2005.04.015"},{"key":"e_1_2_1_22_2","first-page":"127","article-title":"A continuous membrane bioreactor for ester synthesis in organic media: I. 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