Application of the TORO technique of 1H NMR to the structural analysis of cyclic peptide isomers having a slightly distorted symmetry from C2

The extended TORO technique was applied to the structural analysis of endo-D-Tyr-gramicidin S, cyclo(-Val-Orn-Leu-D-Phe-D-Tyr-Pro-Val-Orn-Leu-D-Phe-Pro-), which has a slightly distorted symmetry from C2, by the insertion of D-Tyr and equivalent alpha-proton chemical shifts in the 1H NMR spectrum. All NMR signals of the two dominant isomers of this antibiotic with trans-trans prolines were determined by using the extended TORO technique with TOCSY and ROESY spectra. This technique is generally applicable for distinguishing overlapped signals of alpha- and amide protons from the main chains of peptides.     

Can H2 inside C60 communicate with the outside world?

The quenching rate constants of singlet oxygen by C60, H2@C60, D2@C6o, H2, and D2 in solution were measured. The presence of a hydrogen (H2@C60) or deuterium (D2@C60) molecule inside the fullerene did not produce any observable effect based on triplet lifetime or EPR measurements. However, a remarkable effect was found for the 1O2 quenching by C60, H2@C60, D2@C6o, H2, and D2. Singlet oxygen was generated by photosensitization or by thermal decomposition of naphthalene endoperoxide derivatives. Comparison of the rate constants for quenching of 1O2 by H2@C60 and D2@C60 demonstrates a significant vibrational interaction between oxygen and H2 inside the fullerene. The quenching rate constant for H2 is 1 order of magnitude higher than that of D2, in agreement with the results observed for the quenching of 1O2 with H2@C60 or D2@C60.     

Infrared spectra of (HCOOH)(2) and (DCOOH)(2) in rare gas matrices: a comparative study with gas phase spectra

Infrared absorption spectra of (HCOOH)(2) and (DCOOH)(2) in solid argon, krypton, and xenon matrices have been measured and each fundamental band has been assigned. Spectra in Ar and Kr matrices showed notable splitting in contrast to those in Xe, which suggests a difference in structure of the trapping sites. A comparison with the reported jet-cooled spectra has shown that vibrational structures of the spectra of (HCOOH)(2) and (DCOOH)(2) in the O-H stretching region are preserved in the matrices. On the other hand, the C-O stretching band of (HCOOH)(2) shows a drastic change upon matrix isolation, wherein the Fermi-triad feature observed in gas phase [F. Ito, Chem. Phys. Lett. 447, 202 (2007)] could not be identified. No substantial change of the vibrational structure has been found for matrix-isolated (DCOOH)(2). The differences of the vibrational structures in the matrix-isolation spectra and in the jet-cooled spectra have been qualitatively accounted for using the idea of anharmonic couplings among "matrix-shifted harmonic states."     

Synthesis of an Anthraquinone-Bridged bis(terpyridine) Ligand and its Use in the Stepwise Fabrication of Complex Oligomer Wires on Gold

A new bis(terpyridine) ligand with an anthraquinone linker was synthesized. Stepwise coordination reactions at the gold surface using this ligand gave homo-metal oligomer wires up to pentamer, [ n FeL ₁ ] (n = 1–5), and hetero-metal oligomer wires with ferrocene as the terminal group, [1FeL ₁ 1FeL ₂ Fc] . Electrochemical properties of these modified electrodes were examined.     

Strategies for ensuring that regenerative cardiomyocytes function properly and in cooperation with the host myocardium

In developed countries, in which people have nutrient-rich diets, convenient environments, and access to numerous medications, the disease paradigm has changed. Nowadays, heart failure is one of the major causes of death. In spite of this, the therapeutic efficacies of medications are generally unsatisfactory. Although whole heart transplantation is ideal for younger patients with heart failure, many patients are deemed to be unsuitable for this type of surgery due to complications and/or age. The need for therapeutic alternatives to heart transplantation is great. Regenerative therapy is a strong option. For this purpose, several cell sources have been investigated, including intrinsic adult stem or progenitor cells and extrinsic pluripotent stem cells. Most intrinsic stem cells seem to contribute to a regenerative environment via paracrine factors and/or angiogenesis, whereas extrinsic pluripotent stem cells are unlimited sources of cardiomyocytes. In this review, we summarize the various strategies for using regenerative cardiomyocytes including our recent progressions: non-genetic approaches for the purification of cardiomyocytes and efficient transplantation. We expect that use of intrinsic and extrinsic stem cells in combination will enhance therapeutic effectiveness.     

Thermodynamics for the Formation of Double‐Stranded DNA–Single‐Walled Carbon Nanotube Hybrids

For the first time, the thermodynamics are described for the formation of double‐stranded DNA (ds‐DNA)–single‐walled carbon nanotube (SWNT) hybrids. This treatment is applied to the exchange reaction of sodium cholate (SC) molecules on SWNTs and the ds‐DNAs d(A)₂₀–d(T)₂₀ and nuclear factor (NF)‐κB decoy. UV/Vis/near‐IR spectroscopy with temperature variations was used for analyzing the exchange reaction on the SWNTs with four different chiralities: (n,m)=(8,3), (6,5), (7,5), and (8,6). Single‐stranded DNAs (ss‐DNAs), including d(A)₂₀ and d(T)₂₀, are also used for comparison. The d(A)₂₀–d(T)₂₀ shows a drastic change in its thermodynamic parameters around the melting temperature (T_m) of the DNA oligomer. No such T_m dependency was measured, owing to high T_m in the NF‐κB decoy DNA and no T_m in the ss‐DNA.