Table 3 Activity assessment of the different PAL variants within the ammonia addition and ammonia elimination reactions of para-substituted cinnamic acids 2i–l and rac-phenylalanines 1i–l, respectively.

From: Towards a general approach for tailoring the hydrophobic binding site of phenylalanine ammonia-lyases

  1. n.d. not determinable, during enzyme kinetics the non-linear range of the Michaelis–Menten curve was not obtained using substrate concentration allowed by the solubility of the tested compounds; n.a. no activity detected; “-” no determination/measurement was performed.
  2. #During the ammonia additions the enantiomeric excess of the obtained l-phenylalanine analogues was also monitored, in all cases ee > 99% have been obtained, with marked exceptions.
  3. *1. In case of 2i: PcPAL F137V variant provided l-1i with ee = 97%; AtPAL F136V variant provided l-1i with ee = 93%; 2. in case of 2j: PcPAL F137V variant provided l-1j with ee = 82%; AtPAL F136V variant provided l-1j with ee = 83%; 3. in case of 2k: AtPAL F136V variant provided l-1k with ee = 97%.
  4. **During the kinetic resolution-type ammonia eliminations in case of high enantioselectivity the maximal conversion values of rac-phenylalanines is 50%, conversions exceeding this value, support the low enantioselectivity of the process.
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