l-Phenylalanine ammonia lyase from the lignified and non-lignified regions of Cuscuta chinensis

l-Phenylalanine ammonia lyase (PAL) was not uniformly distributed along the length of Cuscuta chinensis vine but showed alternate zones of high and low activities starting from the tip. The first region of high activity, 0–5 cm from the tip, coincided with high protein and soluble phenolic content. The second zone 17.5–30 cm, coincided with the region of lignification in the secondary xylem. PAL occurs as at least two isoenzymes in the tip and lignified regions and these have been partially purified. The properties of PAL from both the lignified and non-lignified regions could not be distinguished by several criteria including rates of in vivo decay following excision of the vine. Some of the properties of the major isoenzyme of PAL from the tip are reported.