Dear Plant Biochemistry / Plant Enyzme Community,

the elucidation of metabolic pathways in plant specialized metabolism is often faciliated via the heterologous expression of enzymes in eucaryote systems such as yeast or Nicotiana benthamiana. The enzyme products can undergo a number of unspecific reactions in the cell of the heterologous host, the culture medium, during the extraction and during the analysis process.

In a recent review (1) I have listed such unspecific reactions that have so far been observed for the heterologous expression of sesquiterpene modifying enyzmes.

These are mainly:

(I) O-conjugation

(II) S-conjugation

(III) Acid-induced rearrangement (in this case mostly transannular rearrangements)

(IV) Heat-induced rearrangement (in this case Cope rearrangement)

What are your experiences with other kinds of terpenes and also phenylpropanoids and alkaloids? What unspecific reactions have you observed during expression, extraction and GC-MS/LC-MS analysis? What strategies to overcome them have you developed?

(1) Frey, M. 2020. Traps and pitfalls—unspecific reactions in metabolic engineering of sesquiterpenoid pathways. Molecules, 25.