PURIFICATION AND CHARACTERIZATION OF HYDROXYCINNAMOYL-COENZYME-A - OMEGA-HYDROXYPALMITIC ACID O-HYDROXYCINNAMOYLTRANSFERASE FROM TOBACCO (NICOTIANA-TABACUM-L) CELL-SUSPENSION CULTURES

An acyltransferase (hydroxycinnamoyl-Coenzyme A: omega-hydroxypalmitic acid O-hydroxycinnamoyltransferase (HHT; EC 2.3.1.-), which transfers hydroxycinnamic acids from hydroxycinnamoyl-CoA thioesters to several hydroxylated fatty acid derivatives, was characterized from tobacco ( Nicotiana tabacum L. cv. Xanthi nc) cell-suspension cultures. It exhib ited the same properties as the enzyme previously detected in wound-he aling potato tuber discs (Lotfy et al., 1994, Phytochemistry 35: 1419- 1424), and especially a marked specificity for omega-hydroxypalmitic a cid and feruloyl-CoA. It was purified 300-fold to near homogeneity fro m late logarithmic-phase cell suspensions. The apparent molecular mass of the native protein was 55 kDa and its isoelectric point, estimated by electrofocusing, was 4.6. The purified enzyme conjugated ferulic a cid to omega-hydroxypalmitic acid and to 1-tetradecanol, its main lipi dic substrates, suggesting that the same enzyme probably synthesizes t he different esters of l-alkanols and of omega-hydroxy fatty acids whi ch are formed in vitro.