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A new biocatalyst: Penicillin G acylase immobilized in sol‐gel micro‐particles with magnetic properties
Author(s) -
Bernardino Susana M. S. A.,
Fernandes Pedro,
Fonseca Luís P.
Publication year - 2009
Publication title -
biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.144
H-Index - 84
eISSN - 1860-7314
pISSN - 1860-6768
DOI - 10.1002/biot.200800287
Subject(s) - hydrolysis , chemistry , biocatalysis , nuclear chemistry , yield (engineering) , immobilized enzyme , substrate (aquarium) , penicillin amidase , magnetic nanoparticles , catalysis , chromatography , organic chemistry , materials science , enzyme , reaction mechanism , nanoparticle , nanotechnology , oceanography , metallurgy , geology
The present work focuses on the development and basic characterization of a new magnetic biocatalyst, namely penicillin G acylase (PGA), immobilized in sol‐gel 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‐carriers with medium sized particles of 30 μm, as determined by scanning electron microscopy. An immobilization yield of 95–100% and a recovered activity of 50–65% at 37°C, 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‐gel, where only 10% of activity was recovered. The values of activity were kept constant for 6 months. Immobilized PGA (682 U/g dry weight ) retained high specific activity throughout ten consecutive runs for PG hydrolysis, suggesting adequate biocatalyst stability. The CEX synthesis was performed at 14°C, using the free and immobilized PGA in aqueous medium. Phenylglycine methyl ester was used as acyl donor at 90 mM and 7‐aminodeacetoxycephalosporanic acid was the limiting substrate at 30 mM. The CEX stoichiometric yield after 1‐h reaction was close to 68% (23 mM CEX/h) and 65% (19 mM CEX/h), respectively.