We have succeeded in refolding of aggregated recombinant protein from Escherichia coli in hydrated ionic liquids. In cholinium dihydrogen phosphate containing a limited amount of water molecules, aggregated solid cellulase was dissolved and refolding was successfully carried out without further processing.

Dissolution and refolding of aggregated concanavalin A were demonstrated in hydrated ionic liquids.

The NMR chemical shift variation of H₂O varied with the component ion and reflected the kosmotropicity quantitatively in hydrated ionic liquids.

Recently, extensive efforts have been made to understand the importance of the extra-renal uric acid (UA) excretion pathways and their contribution to UA-related diseases. However, the method typically used to measure UA concentrations in the intestinal lumen is difficult to real time and dynamic analysis. In this study, UA excretion in the rat intestinal lumen was measured in real time using an electrochemical method. A sensitive electrode to detect UA was constructed using a gold electrode modified with a mixed self-assembled monolayer. Excretion rate of UA in the intestine was calculated using time course data. A decrease in UA excretion rate was observed in the intestine after administration of serum UA-lowering drugs (benzbromarone, febuxostat, and topiroxostat). Inhibition of ATP-binding cassette transporter G2 (ABCG2) which has been reported as an important exporter of UA was suggested by administration of these drugs. On the other hand, an increase in excretion rate of UA was observed in the intestine of 5/6 nephrectomy rats. Upregulation of mRNA expression of the UA transporter organic anion transporter OAT3, which is related to the secretion at the basal membrane, suggested an enhancement of UA excretion by ABCG2, a high-capacity UA exporter. Observed urate excretion dynamics and mRNA expression of UA transporters in the intestine upon administration of serum UA-lowering drugs and 5/6 nephrectomy improve our understanding of the underlying mechanisms of intestinal UA excretion.

Ionic liquid (IL)/water biphasic systems have received a large amount attention because of their application as extraction media for many compounds; in particular, IL/water mixtures with lower critical solution temperature (LCST)-type phase transitions have been successfully applied to the selective extraction of proteins. However, the reversible control of protein distribution in IL/water biphasic mixtures has not yet been explored. This study investigates the change in distribution of cytochrome c (cyt c) in a mixture of tetrabutylphosphonium 2,4,6-trimethylbenzenesulfonate ([P_4,4,4,4][TMBS]), which has LCST behavior, and a potassium phosphate buffer (PKB) with temperature variation. Absorbance measurements of cyt c in the two phases show that oxidized cyt c was transferred into the [P_4,4,4,4][TMBS] phase via the LCST behavior, whereas reduced cyt c remained in the PKB phase. Based on the distribution of cyt c in the [P_4,4,4,4][TMBS]/PKB mixture, which depends on the redox state, we propose a system to reversibly transfer cyt c in the biphasic mixture by applying potential and temperature gradients. The calculated redox potentials suggest that oxidized cyt c is more stable than its reduced form in the [P_4,4,4,4][TMBS]/PKB mixture.