@article{xiong_shen_wang_chen_2019, title={Measurements and correlation of liquid-liquid equilibrium data for the ternary (methyl tert-butyl ketone plus o, m, p-benzenediol plus water) system at (333.2, 343.2 and 353.2) K}, volume={27}, ISSN={["2210-321X"]}, DOI={10.1016/j.cjche.2018.09.011}, abstractNote={Abstract In this work, liquid–liquid equilibria (LLE) data for the ternary system methyl tert-butyl ketone (MTBK) + o, m, p-benzenediol + water were investigated at 333.2 K, 343.2 K and 353.2 K under 101.3 kPa. The performance of MTBK to extract o, m, p-benzenediol from wastewaters was estimated by partition coefficients and separation factors. The Hand and Bachman equations were both applied to check the reliability of the experimental LLE data. Furthermore, the Non-Random Two-Liquid (NRTL) and Universal Quasi Chemical (UNIQUAC) models were applied to correlate the measured LLE data. The results showed a good agreement with the determined ternary LLE data with the root-mean-square error (RMSE) values below 0.71%. MTBK was proved to be a promising extracting agent in extracting benzenediols from effluents.}, number={4}, journal={CHINESE JOURNAL OF CHEMICAL ENGINEERING}, author={Xiong, Kangning and Shen, Shuai and Wang, Youchang and Chen, Yun}, year={2019}, month={Apr}, pages={905–911} } @article{chen_clark_2006, title={Substitutions of prolines examine their role in kinetic trap formation of the caspase recruitment domain (CARD) of RICK}, volume={15}, ISSN={["1469-896X"]}, DOI={10.1110/ps.051943006}, abstractNote={Caspase recruitment domains (CARDs) are small helical protein domains that adopt the Greek key fold. For the two CARDs studied to date, RICK-CARD and caspase-1-CARD (CP1-CARD), the proteins unfold by an apparent two-state process at equilibrium. However, the folding kinetics are complex for both proteins and may contain kinetically trapped species on the folding pathway. In the case of RICK-CARD, the time constants of the slow refolding phases are consistent with proline isomerism. RICK-CARD contains three prolines, P47 in turn 3, and P85 and P87. The latter two prolines constitute a nonconserved PxP motif in helix 6. To examine the role of the prolines in the complex folding kinetics of RICK-CARD, we generated seven proline-to-alanine mutants, including three single mutants, three double mutants, and one triple mutant. We examined the spectroscopic properties, equilibrium folding, binding to CP1-CARD, and folding kinetics. The results show that P85 is critical for maintaining the function of the protein and that all mutations decrease the stability. Results from single mixing and sequential mixing stopped-flow studies strongly suggest the presence of parallel folding pathways consisting of at least two unfolded populations. The mutations affect the distribution of the two unfolded species, thereby affecting the population that folds through each channel. The two conformations also are present in the triple mutant, demonstrating that interconversion between them is not due to prolyl isomerism. Overall, the data show that the complex folding pathway, especially formation of kinetically trapped species, is not due to prolyl isomerism.}, number={3}, journal={PROTEIN SCIENCE}, author={Chen, YR and Clark, AC}, year={2006}, month={Mar}, pages={395–409} } @article{chen_clark_2004, title={Kinetic traps in the folding/unfolding of procaspase-1 CARD domain}, volume={13}, ISSN={["1469-896X"]}, DOI={10.1110/ps.03521504}, abstractNote={We have examined the folding and unfolding of the caspase recruitment domain of procaspase-1 (CP1-CARD), a member of the alpha-helical Greek key protein family. The equilibrium folding/unfolding of CP1-CARD is described by a two-state mechanism, and the results show CP1-CARD is marginally stable with a DeltaG(H2O) of 1.1 +/- 0.2 kcal/mole and an m-value of 0.65 +/- 0.06 kcal/mole/M (10 mM Tris-HCl at pH 8.0, 1 mM DTT, 25 degrees C). Consistent with the equilibrium folding data, CP1-CARD is a monomer in solution when examined by size exclusion chromatography. Single-mixing stopped-flow refolding and unfolding studies show that CP1-CARD folds and unfolds rapidly, with no detectable slow phases, and the reactions appear to reach equilibrium within 10 msec. However, double jump kinetic experiments demonstrate the presence of an unfolded-like intermediate during unfolding. The intermediate converts to the fully unfolded conformation with a half-time of 10 sec. Interrupted refolding studies demonstrate the presence of one or more nativelike intermediates during refolding, which convert to the native conformation with a half-time of about 60 sec. Overall, the data show that both unfolding and refolding processes are slow, and the pathways contain kinetically trapped species.}, number={8}, journal={PROTEIN SCIENCE}, author={Chen, YR and Clark, AC}, year={2004}, month={Aug}, pages={2196–2206} }