In a recent paper in the Journal of Molecular Evolution (49:453-460) entitled "Respiratory Chains in the Last Common Ancestor of Living Organisms", the authors have compared the sequence of enzymes involved in respiratory chains for oxygen, sulfate, and nitrate metabolism. Based on the similarity between eubacteria, eukaryotes and archeans, they conclude that the Last Common Ancestor [i.e. the ultimate cell that gave rise to all three groups] had all of these chains intact!
The authors wrote:
Even if we had a proven mechanism for evolutionary increases in information content of living systems (and we don't), there is virtually no chance that such intricate metabolic pathways involving the use of oxygen as an electron acceptor could have evolved in the absence of oxygen. This finding poses yet another fatal challenge to the naturalistic explanation for the origin of life on this planet.
2010 Arthur V. Chadwick, Ph.D.