Major Compatible Solutes and Structural Adaptation of Proteins in Extremophiles

Extremophiles are the most ancient microbes on the Earth and also a center of attraction for the scientific community for research because of their ability to adapt to extreme habitats. Compatible solutes are among those factors which enable these microorganisms to thrive in such extreme habitats. Under osmotic stress, the majority of extremophiles accumulate specific organic solutes such as amino acids, sugars, polyols, and their derivatives. In addition, proteins in extremophiles are found to be evolved by changing their amino acid composition to alter the hydrophobicity of its core and surface charge to maintain activity. This chapter encompasses a comprehensive study about the role of various compatible solutes in the endurance of microorganisms under extremophilic conditions, synthesis of compatible solutes, nature of extremophilic proteins, and their applications. Furthermore, an attempt has been made to cover various strategies adopted by the scientific community while pursuing research on compatible solutes.

Imidazolium Based Ionic Liquids: Unbiased Recovering of Vaporization Enthalpies from Infinite-Dilution Activity Coefficients

We propose and test an efficient approach for the assessment of the enthalpies of vaporization of ionic liquids at the reference temperature 298.15 K. The approach is based on activity coefficients at infinite dilution of volatile organic solutes in ionic liquids bearing the imidazolium cation of the general formula [Cnmim][Anion].

Impaired Tubular Secretion of Organic Solutes in Advanced CKD

Background The clearance of solutes removed by tubular secretion may be altered out of proportion to the glomerular filtration rate (GFR) in chronic kidney disease (CKD). Recent studies have described considerable variability in the secretory clearance of waste solutes relative to the GFR in patients with CKD. Methods To test the hypothesis that secretory clearance relative to GFR is reduced in patients approaching dialysis, we used metabolomic analysis to identify solutes in simultaneous urine and plasma samples from 16 CKD patients with an estimated GFR of 7±2 ml/min per 1.73m2 and 16 control participants. Fractional clearances were calculated as the ratios of urine to plasma levels of each solute relative to those of creatinine and urea in CKD patients and to those of creatinine in controls. Results Metabolomic analysis identified 39 secreted solutes with fractional clearance >3.0 in control participants. Fractional clearance values in CKD patients were reduced on average to 65%±27% of those in controls. These values were significantly lower for 18 of 39 individual solutes and significantly higher for only one. Assays of the secreted anions phenylacetyl glutamine, p-cresol sulfate, indoxyl sulfate, and hippurate confirmed variable impairment of secretory clearances in advanced CKD. Fractional clearances were markedly reduced for phenylacetylglutamine (4.2±0.6 for controls versus 2.3±0.6 for CKD patients, P<0.001), p-cresol sulfate (8.6±2.6 for controls versus 4.1±1.5 for CKD patients, P<0.001), and indoxyl sulfate (23.0±7.3 versus 7.5±2.8, P<0.001), but not for hippurate (10.2±3.8 versus 8.4±2.6, P=0.13). Conclusions Secretory clearances for many solutes are reduced more relative to the reduction in GFR in advanced CKD. Impaired secretion of these solutes might contribute to uremic symptoms as patients approach dialysis.