Figure 2.

Investigation of the stability of intact ribosomes in the presence of Mg²⁺ and after cross-liking of ribosomal proteins to rRNA. Nanoflow electrospray mass spectra of (A) 50S and (B) 70S ribosome particles in the presence of 5 mM Mg²⁺, (C) after a 3-fold dilution of the solution, and (D) after cross-linking by exposure to UV radiation. The overall quality of the spectrum is affected by the presence 5 mM Mg²⁺ in the sample buffer (B), an improvement in the signal-to-noise ratio is observed when the solution is diluted 3-fold (C) and in the absence of Mg²⁺ in the spectrum of the cross-linked particle (D). The mass spectra were recorded on the LCT mass spectrometer with collisional damping to maintain the integrity of the intact particles. The spectrum of the cross-linked ribosome (D) was recorded with a cone voltage of 200 V and with reduced pressure in the hexapole region.