Protein chemotaxonomy of genus Datura: identical amino acid sequence of ferredoxin from two varieties of Datura stramonium.

The complete amino acid sequence of the respective [2Fe-2S] ferredoxins from two varieties of Datura stramonium, D. stramonium var. stramonium and D. stramonium var. tatula, have been determined by automated Edman degradation of the entire Cm-protein and of the peptides obtained by tryptic digestion and CNBr treatment. The ferredoxins from the two plants exhibited identical amino acid sequences, suggesting a very close taxonomic relationship between the two. This result supports the proposal by Blakeslee and others that these plants, at first named by Linnaeus as two distinct species, i.e. D. stramonium L. and D. tatula L., should be considered two varieties of a single species.