Abstract

The amino acid sequence of Paracoccus (formerly Micrococcus) denitrificans cytochrome c550 has been established by a combination of standard chemical techniques and interpretation of a 2.5 A resolution x-ray electron density map. Peptides derived from a trypsin digest were chemically sequenced, and then ordered by fitting them to the density map. The amino acid compositions of chymotryptic peptides confirmed the x-ray map ordering the tryptic peptides. The amino acid sequence of this respiratory, prokaryotic cytochrome with 134 residues is discussed in relation to those of eukaryotic respiratory cytochrome c (103 to 113 amino acids), and prokaryotic, photosynthetic c2 (103 to 124 amino acids). At the primary structure level, c and c550 differ no more from cytochromes c2 than the various cytochromes c2 do from one another. It is suggested that the respiratory electron transport chain in prokaryotes and eukaryotes is a relatively late evolutionary offshoot of the photosynthetic electron transport chain in purple non-sulfur bacteria.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.