Improved enzymatic two-phase biotransformation for (R)-phenylacetylcarbinol: Effect of dipropylene glycol and modes of pH control

• Published in: Biocatalysis and biotransformation Vol. 23; no. 6; pp. 445 - 451
• Main Authors: Leksawasdi, Noppol, Rogers, Peter L., Rosche, Bettina
• Format: Journal Article
• Language: English
• Published: Abingdon Informa UK Ltd 01.01.2005; Taylor & Francis; Taylor and Francis
• Subjects: (R)-phenylacetylcarbinol; Bioconversions. Hemisynthesis; Biological and medical sciences; Biotechnology; Biotransformation; enzyme activity; Fundamental and applied biological sciences. Psychology; Methods. Procedures. Technologies; organic-aqueous two-phase system; pH control; pyruvate decarboxylase; Enzyme; pH control; Lyases; organic-aqueous two-phase system; Carbon-carbon lyases; Biphasic system; (R)-phmylacetylcarbinol; Enzymatic activity; Carboxy-lyases; Biotransformation; enzyme activity; pH; Pyruvate decarboxylase; Enzymatic reaction
• ISSN: 1024-2422; 1029-2446
• DOI: 10.1080/10242420500444135

An octanol/aqueous two-phase process for the enzymatic production of (R)-phenylacetylcarbinol (PAC) has been investigated further with regard to optimal pH control and replacement of 2.5 M MOPS buffer by a low cost solute. The specific rate of PAC production in the 2.5 M MOPS system controlled at pH 7 was 0.60 mg U−1 h−1 (reaction completed at 34 h), a 1.6 times improvement over the same 2.5 M MOPS system without pH control (0.39 mg U−1 h−1 at 49 h). An improved stability of PDC was evident at the end of biotransformation for the pH-controlled system with 84% residual carboligase activity, while 23% of enzyme activity remained in the absence of pH control. Lowering the MOPS concentration to 20 mM resulted in a lower benzaldehyde concentration in the aqueous phase with a major increase in the formation of by-product acetoin and three times decreased PAC production (0.21 mg U−1 h−1). Biotransformation with 20 mM MOPS and 2.5 M DPG as inexpensive replacement of high MOPS concentrations provided similar aqueous phase benzaldehyde concentrations compared to 2.5 M MOPS and resulted in a comparable PAC concentration (92.1 g L−1 in the total reaction volume in 47 h) with modest formation of acetoin.