Penicillin Acylase Catalysed Synthesis of Ampicillin in Hydrophilic Organic Solvents

Abstract

Penicillin acylase (EC 3.5.1.11) from Alcaligenes faecalis, immobilised as a cross-linked enzyme aggregate (CLEA), catalysed the synthesis of ampicillin in water-miscible organic solvents at low water concentrations. Below 4% water (v/v) no reaction was observed, showing the crucial role of water in maintaining the activity of penicillin acylase. The initial value of S/H was strongly affected by the nature of the solvent, but the effect of the water content was slight in the studied range of 4 to 15%. A reaction in acetonitrile containing 8% water afforded ampicillin in up to 86% yield.

Enzyme Immobilization: The Quest for Optimum Performance

“…Analogous to the corresponding CLECs, the penicillin G amidase CLEAs also maintained their high activity in organic solvents. [97,98] CLEAs were subsequently prepared from seven commercially available lipases (EC 3.1.1.3) and the effects of various parameters, such as the precipitant and the addition of additives such as surfactants and crown ethers, on their activities were investigated. [99] The activation of lipases by additives, such as surfactants and crown ethers, is well-documented and is generally attributed to the lipase being induced to adopt a more active conformation.…”

Immobilization of Penicillin G Acylase: The Key to Optimum Performance

“…High (up to 86%) ampicillin yields resulted from reactions in acetonitrile medium in the presence of a CLEA of the relatively unknown penicillin G acylase from Alcaligenes faecalis. [90] A minimum water activity of 0.4 -0.7 was required for enzymatic activity, [90] which is in the same range as required by penicillin G acylase on Celite R-640. [77] CLEAs: Concluding Remarks Penicillin G acylase CLEAs are highly active and stable preparations with an impressive synthetic capability.…”

Improved β-lactam acylases and their use as industrial biocatalysts

“…On the one hand, the screening of different co-solvents showed some of them to have a similar effect on the pK of the carboxylic acid, but a low deleterious effect on PGA stability. A reaction in acetonitrile containing 8% water afforded ampicillin in up to 86% yield using the more stable PGA from Alcaligenes faecalis [36]. Also, the yield of cephalexin could be increased significantly by using an aqueous two-phase system containing 20% (w/w) polyethylene glycol (PEG) 400 and 15% (w/w) magnesium sulfate, because the inhibiting product accumulated separately from the enzyme in the PEG phase [37].…”