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Penicillin acylase‐catalyzed ampicillin synthesis using a pH gradient: A new approach to optimization
Author(s) -
Youshko Maxim I.,
van Langen Luuk M.,
de Vroom Erik,
van Rantwijk Fred,
Sheldon Roger A.,
Švedas Vytas K.
Publication year - 2002
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.10234
Subject(s) - chemistry , hydrolysis , ampicillin , penicillin amidase , penicillin , catalysis , amide , catalytic efficiency , saturation (graph theory) , chromatography , enzyme , immobilized enzyme , organic chemistry , antibiotics , biochemistry , mathematics , combinatorics
The penicillin acylase‐catalyzed synthesis of ampicillin by acyl transfer from D‐(–)‐phenylglycine amide (D‐PGA) to 6‐aminopenicillanic acid (6‐APA) becomes more effective when a judiciously chosen pH gradient is applied in the course of the process. This reaction concept is based on two experimental observations: 1) The ratio of the initial synthesis and hydrolysis rates (V S /V H ) is pH‐dependent and exhibits a maximum at pH 6.5–7.0 for a saturated solution of 6‐APA; 2) at a fixed 6‐APA concentration below saturation, V S /V H increases with decreasing pH. Optimum synthetic efficiency could, therefore, be achieved by starting with a concentrated 6‐APA solution at pH 7 and gradually decreasing the pH to 6.3 in the course of 6‐APA consumption. A conversion of 96% of 6‐APA and 71% of D‐PGA into ampicillin was accomplished in an optimized procedure, which significantly exceeds the efficiency of enzymatic synthesis performed at a constant pH of either 7.0 or 6.3. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 589–593, 2002.