Study on enzymology properties of L-phenylalanine ammonia-lyase(PAL) in litchi fruit

The enzymology properties of L-phenylalanine ammonia-lyase(PAL) was investigated in this study.Litchi PAL dynamic curve did not follow the Michaelis-Menten equation. The optimum substrate concentration was 2 mmol/L. In the borax-boric acid buffer,the optimum reaction p H value was 8.7. Litchi PAL did not resistant to acid and alkali,especially to acid. The optimum reaction temperature was 45 ℃,and if the temperature was higher than 75 ℃,Litchi PAL was easily passivated. Litchi PAL had strong heat resistance. L-tyrosine and L-cysteine had significant inhibitory effect on Litchi PAL. Among the metal irons,Fe2+and Fe3+had significant promoting effect on PAL,while Ca2+,Cu2+,Co2+and Ag+had significant inhibitory effect on Litchi PAL.