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Publication
Penicillin G acylase encapsulation studies in polyvinyl alcohol based matrices
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Advisor(s)
Abstract(s)
Penicillin G acylase (EC 3.5.1.11) (PGA) hydrolyses penicillin G (PG) producing 6-aminopenicillanic acid (6-APA), an important building block in the synthesis of semi-synthetic antibiotics such as ampicillin and amoxicillin. The synthesis of these antibiotics by PGA is already successfully used in lab and pilot scales and more recently in the synthesis of cefalexin (CEX) at industrial scale. This work characterizes the stability and activity of PGA when immobilized in a polyvinyl alcohol based matrix (Lentikat® liquid), PVA/LL by a new and simple entrapment strategy. The biocatalyst retains from 22 to 66% of its original activity, depending on enzyme load. Hydrolysis and synthesis reactions were tested and the immobilized enzyme can be reused for, at least, 10 consecutive batches without decay of initial activity. The preferential pH and temperature for the hydrolysis of PG are 8 and 37ºC, respectively, it is stable at 4ºC and its half-life, at 25ºC and pH 8 is roughly 8 days. For the synthesis of CEX there was no decay of initial activity for at least 50 hours, at 14ºC and pH 7.2, which indicates a high operational stability. Substrate inhibition by 7-aminodesacetoxicefalosporanic acid (7-ADCA) was observed both for the free and the immobilized enzyme. These forms of enzyme presented synthesis of CEX and hydrolysis of PGM ratio (S/H) of 4.2 and 2.5, respectively. The biocatalyst (PGA_PVA beads) is suitable for the production of cefalexin in industry since it showed a high operational stability, without enzyme leakage during the reaction and between washing steps.
Description
Dissertação mest., Biotecnologia, Universidade do Algarve, 2009
Keywords
Teses Penicilina Antibióticos