Ionic Liquid-Induced Unique Structural Transitions of Proteins

The structural transitions of proteins in aqueous solutions of various ionic liquids (ILs) over a wide concentration range (x (mol% IL) = 0–30) were investigated using Fourier-transform infrared and near-UV circular dichroism spectroscopy combined with small-angle X-ray scattering. The proteins in the aqueous IL solutions showed two structural transition patterns: (i) the folded state → unfolded state → partial globular state (α-helical formation disrupted tertiary structure) and (ii) the folded state → unfolded state → aggregation (amyloid-like aggregation or disordered aggregation). We found that the helical formation of proteins in the condensed IL solutions was strongly related to the competition between the low polarity and denaturation effect of ions. Moreover, the amyloid-like aggregate formation correlated with the competition between the size of the confined water assemblies in the IL layer and the IL-amino acid residue interactions. On the basis of these results, we discussed the future applications of ILs, including their use as cryoprotectants for proteins and as agents for the suppression of amyloid formation

Effect of rehabilitation in patients undergoing hematopoietic stem cell transplantation

Patients undergoing hematopoietic stem cell transplantation (HSCT) tend to experience decline in physical function, mental function, and quality of life (QOL) after HSCT due to low activity caused by adverse reactions to chemotherapy used in pre-transplantation treatment and post-transplant complications. Rehabilitation for HSCT patients is effective in preventing decline in physical function, reducing fatigue, and improving QOL. A combination of aerobic exercise and strength training is recommended for exercise therapy. Risk management is also important in the implementation of exercise therapy, and the exercise intensity should be determined according to the presence of anemia, low platelet counts, or post-transplant complications. On the other hand, post-transplant complications can decrease the patient's motivation and daily activity level. A multidisciplinary approach, which includes physicians and nurses, is important to achieve early discharge from the hospital and as quick a return to society as possible

Conformational Analysis of Quaternary Ammonium-Type Ionic Liquid Cation, N,N-Diethyl-N-methyl-N-(2-methoxyethyl) Ammonium Cation

Conformational preference of N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium cation ([DEME]+), which is one of the quaternary ammonium-based ionic liquid cation, in the gas phase has been investigated using a density functional theory (DFT) calculation. Eight candidates for the stable conformers of [DEME]+ exist in the gas phase, and can it energetically classify into two groups. One is a five conformers group, which has the N+⋯O− intramolecular attractive interaction form (the folded form). The other is a three conformers group, which is the noninteraction form (the extended form). The transformation from the folded form to the extended form induces large changes in the dipole moment and partial charges of N and O atoms. Here we show that the difference in the dipole moment and partial charges of N and O atoms associated with the conformational change of [DEME]+ are closely related to the molecular orientation of [DEME]-based ionic liquids in the liquid state

Theoretical study of volume changes associated with the helix-coil transition of an alanine-rich peptide in aqueous solution

The changes in the partial molar volume (PMV) associated with the conformational transition of an alanine-rich peptide AK16 from the alpha-helix structure to various random coil structures are calculated by the three-dimensional interaction site model (3D-RISM) theory coupled with the Kirkwood-Buff theory. The volume change is analyzed by decomposing it into contributions from geometry and hydration: the changes in the van der Waals, void, thermal, and interaction volume. The total change in the PMV is positive. This is primarily due to the growth of void space within the peptide, which is canceled in part by the volume reduction resulting from the increase in the electrostatic interaction between the peptide and water molecules. The changes in the void and thermal volume of the coil structures are widely distributed and tend to compensate each other. Additionally, the relations between the hydration volume components and the surface properties are investigated. We categorize coil structures into extended coils with the PMV smaller than helix and general coils with the PMV larger than helix. The pressure therefore can both stabilize and destabilize the coil structures. The latter seems to be a more proper model of random coil structures of the peptide. ? 2005 Wiley Periodicals, Inc. Biopolymers 79: 97-105, 2005This article was originally published online as an accepted preprint. The ldquoPublished Onlinerdquo date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at [email protected] publication: Ye