In the early days of ribosome research, before the exact role of ribosomes was clear, a researcher made the following observation. She could find, in sedimentation experiments on bacterial lysates, not only 30S, 50S, and 70S particles, but also some particles that sedimented at about 100S and 130S. When she treated such a mixture with EDTA, everything dissociated to 30S and 50S particles. Upon adding divalent ions, she could regain 70S particles, but never 100S or 130S particles.
(a) Suggest what the 100S and 130S particles might represent, in light of cur-rent knowledge of protein synthesis. What important discovery did the researcher miss?
(b) Why do you think reassociation to 100S and 130S particles did not work?