Enhancement of l-Phenylalanine production by β-cyclodextrin Original Research Article

The elimination of the inhibition of t-Ca (trans-cinnamic acid) on Phenylalanine ammonia-lyase (PAL, EC4.1.3.5) in the enzymatic reaction and the enhancement of l-Phenylalanine (l-Phe) production by β-cyclodextrin (β-CD) were studied in this work. At the optimum molar ratio of β-CD to t-Ca of 0.13, the lowest inhibitory concentration of t-Ca increases from 135 mmol/l to 270 mmol/l and the l-Phe productivity increases to 266.7% of that without the addition of β-CD at 270 mmol/l t-Ca. Furthermore, with the fed-batch addition of t-Ca at 270 mmol/l t-Ca, the l-Phe productivity reaches 45.9 mmol/l, 302.0% of that without the additions. The effect of β-CD on the substrate inhibition of t-Ca is depicted by kinetic experiments, γMAX increases from 120.3 mmol/l min to 282.5 mmol/l min, Ki increases from 75.1 mmol/l to 1366 mmol/l and Km decreases from 242.5 mmol/l to 53.3 mmol/l.