The amino acid sequences of cytochrome c from four plant sources

Proposed amino acid sequences of cytochrome c from nasturtium (Tropaeolum majus L.), box-elder (Acer negundo L.), elder (Sambucus nigra L.) and parsnip (Pastinaca sativa L.) are presented. Because of the very limited amounts of cytochrome available from some plant sources, peptides derived from the cytochromes c have been sequenced by the semi-quantitative dansyl-Edman technique (Gray & Hartley, 1963) without supporting quantitative amino acid analyses. Because of the qualitative nature of the work, the sequences proposed must be regarded as tentative. Considerations of homology, although useful as a guide, have been kept to a minimum in the construction of sequences. Only the nasturtium sequence relies on considerations of homology for a complete ordering of the peptides. Where material permitted, each residue of a proposed sequence was determined at least once from both a tryptic and a chymotryptic peptide.