The biosynthesis of cinnamoylputrescines in callus tissue cultures of Nicotiana tabacum

Abstract

Extracts of callus of Nicotiana tabacum cv Xanthi n.c. catalyse the formation of caffeoylputrescine from caffeoyl-CoA and putrescine. The enzyme caffeoyl-CoA putrescine N-caffeoyl transferase is soluble, with a M r of ca 48 000. It is not specific for putrescine since cadaverine, agmatine and spermidine are also conjugated to caffeoyl-CoA in the crude enzymic extract. The coenzyme A derivatives of ferulic, cinnamic, sinapic and coumaric acids also act as substrates in the PCT assay, although they are less active than caffeoyl-CoA. PCT activity is stable in vitro when it is extracted with Tris buffer containing 1% ascorbic acid. In vivo spermidine is a precursor of p-coumaroylspermidine, and also of cinnamoylputrescines. Feeding experiments suggest that putrescine and spermidine can be rapidly interconverted.