One of the most important factors influencing enzyme activity is pH. The yield of t-CA in Tris-HCl, phosphate and borate buffers was 0.53 (+/-
0.03), 0.52 (+/-0.07), and 0.52 (+/-0.04) units, respectively; indicating that the nature of
buffer did not have a significant effect on enzyme activity. Since Tris-HCl has generally
been the buffer of choice when working with PAL [16-20], the effect of pH on t-CA
formation in 50.0 mM Tris-HCl buffer was further investigated and the results are shown
in Fig. 3. The pH-enzyme activity curve was not a typical bell-shaped curve but had a maximum at pH 9.0. It is pertinent to mention here that almost all previous studies on the
effect of pH on PAL activity have reported that the optimum pH is in the range of 8.5 –
9.0