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Ribosomes from the gram-negative α-proteobacterium Caulobacter crescentus were isolated using standard methods. Proteins were separated using a two-dimensional liquid chromatographic system that allowed the analysis of whole proteins by direct coupling to an ESI-QTOF mass spectrometer and of proteolytic digests by a number of mass spectrometric methods. The masses of 53 of 54 ribosomal proteins were directly measured. Protein identifications and proposed post-translational modifications were supported by proteolysis with trypsin, endoprotease Glu-C and exoproteases carboxypeptidases Y and P. Tryptic peptide mass maps show an average sequence coverage of 62%, and carboxypeptidase C-terminal sequence tagging provided unambiguous identification of the small, highly basic proteins of the large subunit. C. crescentus presents some post-translational modifications that are similar to those of E. coli (e. g. N-terminal acetylation of S9 and S18) along with some unique variations, such as a near absence of L7 and extensive modification of L11. The comprehensive description of this organism's ribosomal proteome provides a foundation for the study of ribosome structure, dependence of post-translational modifications on growth conditions, and the evolution of subcellular organelles.

The equilibrium solubilities of benzoic acid (BA), salicylic acid (SAL), and acetylsalicylic acid (ASA) were determined in binary (solute + CO 2 ), ternary (two solutes + CO 2 ), and quaternary systems (three solutes + CO 2 ) at temperatures ranging from (308 to 328) K and pressures ranging from (10.1 to 28.0) MPa. Solubility data were obtained using a dynamic approach with a simple and reliable apparatus. Polar mixed-solid solute systems demonstrated solubility enhancements, which were consistent with the entrainer effect. In all the polar ternary systems studied, at least one component exhibited solubility enhancements. In the polar quaternary system studied, the solubility of each component increased in comparison to each binary system; the solubility of ASA, SAL, and BA was enhanced up to 484 %, 248 %, and 43 %, respectively. The high solubility enhancements observed in our study indicate that solute-solute interactions are significant in the supercritical fluid (SCF) phase. The solubility enhancements observed in the polar mixed-solid solute systems studied resulted in a decrease in selectivity of SCF CO 2 . However, in a quaternary system consisting of BA, SAL, and fluoranthene (FLU), the selectivity of SCF CO 2 for SAL versus FLU increased by a factor of 2.7 due to specific solute-solute interactions. This study showed that solute-solute interactions in mixed solid solute systems can result in an increase in the solubility of solutes and also the selectivity of SCF CO 2 .

The binary (solute + CO2) equilibrium solubilities of six substituted phenols (2,5-dimethyl phenol, 2,3-dimethyl phenol, 2,4,6-trimethyl phenol, 2,3,5-trimethyl phenol, 4-phenyl phenol, and 4-tert-butyl phenol) were determined at a temperature of 308 K in the pressure range of 10.1 to 28.0 MPa. Solubility data were obtained using a dynamic approach with a simple and reliable apparatus. The mole fraction solubilities of substituted phenols ranged from 5.14 × 10-5 to 2.56 × 10-2. Solubilities of three ternary (two solutes + CO2) systems were investigated at a temperature of 308 K in the pressure range of 10.1 to 28.0 MPa. In the 4-phenyl phenol + 2,3,5-trimethyl phenol and 4-phenyl phenol + 2,4,6-trimethyl phenol systems, the solubility of 4-phenyl phenol was enhanced relative to its binary solubility by 22.9 % and 217 %, respectively. The 2,3,5-trimethyl phenol and 2,4,6-trimethyl phenol did not exhibit any solubility enhancements in the two ternary systems. Accurate solubilities could not be measured for the 2,5-dimethyl phenol + 4-tert-butyl phenol ternary system due to the existence of a liquid phase under the conditions studied.

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