FIG. 4.

Nanoelectrospray MS spectrum of HQDO directly infused from capillaries using gentle conditions. This spectrum shows two charge envelopes. The first charge distribution at m/z 1,000 to 3,000 with charges from +10 to +20 corresponds to a protein of 30 kDa, which is likely the translation elongation factor Ts. The second charge distribution at m/z 5,000 to 6,000 with charges between +19 to +22 reveals a mass of 112 kDa and corresponds to the intact HQDO protein complex. The instrument settings were chosen such that no fragmentation of the protein assembly occurs. In the insets, the transformation of the charge envelopes to their molecular masses is shown. , HQDO α2β2 tetramer.