Indole-3-Pyruvic Acid as an Intermediate in the Conversion of Tryptophan to Indole-3-Acetic Acid. II. Distribution of Tryptophan Transaminase Activity in Plants

Extracts from different organs of 30 plant species belonging to 16 families have been analysed for tryptophan transaminase activity. Only the brown alga Fucus spiralis was found to be devoid of the enzymes. Among the other plants tested, a difference in activity of two orders of magnitude was recorded. None of the genera or families investigated could be considered as particularly rich or poor sources of the enzyme. Extracts from leaves and stem tips contained generally more transaminase activity than extracts from stems and roots. The results are discussed in relation to other reports on the occurrence of the enzyme in plants.