Takuzo Kurotsu

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A systematic investigation of the effect of acid on the denaturation of some 20 monomeric proteins indicates that several different types of conformational behavior occur, depending on the protein, the acid, the presence of salts or denaturant, and the temperature. Three major types of effects were observed. Type I proteins, when titrated with HCl in the(More)
We report a novel self-assembling system of amphiphilic oligopeptides composed of alternating hydrophobic and ionizable amino-acid residues. Three types of peptides, AD12, AE12 and AK12, were prepared as building blocks for this model system. These peptides formed helical conformations in low-concentration solutions, but these peptides adopted b-sheet(More)
To analyze a curing process of epoxy resin in terms of molecular motion, we adapted a pulsed NMR method. Three kinds of (1)H spin-spin relaxation times (T(2L) (long), T(2S) (short) and T(2M) (intermediate)) were estimated from observed solid echo train signals as the curing process proceeded. A short T(2S) value below 20 micros suggests the existence of a(More)
Interactions between poly alpha- L-glutamic acid (PGA) and metal ions Cd(2+), Co(2+) were studied by direct current polarography. The diffusion currents of these ions decreased sharply in the presence of PGA in the pH region from 5.0 through neutral. A corresponding increase in the helix content of the PGA-metal ion complex was revealed by CD measurements(More)
The proton spin-spin relaxation time (T2) during the bulk polymerization of methyl acrylate was measured as a function of the reaction time at various temperatures. Three kinds of T2 (T2L (long), T2S (short) and T2M (intermediate)) were obtained as the polymerization proceeded. The fraction of T2S (FS) increased sigmoidally at a certain reaction time, while(More)
Helix-coil transitions of poly α-aspartic acid (PASP) were studied by dc polarography in the presence of Zn(2+) as a marker attached to the polymer. The diffusion current (i(d)) of Zn(2+) declined markedly in the pH range of 3.5-7.4 due to a formation of metal ion-PASP macromolecular complexes. The complex formation also reflects on an increase of the(More)
Helix-coil transition of poly aspartic acid (PASP) was investigated by dc polarography in the presence of Cd2+ and/or Zn2+ as a detecting marker which attached to the polymer. The diffusion currents (id) of Cd2+ and Zn2+ decreased sharply in the pH range of 3.5-7.0 due to the formation of the metal ions-PASP macromolecular complexes. The complex formation(More)
We investigated the effect of deformation of natural rubbers (NR) resulting from the high centrifugal pressure of fast magicangle spinning (MAS) on 13C NMR spectra. The solid state 13C MAS NMR spectrum with high-power 1H dipolar decoupling (DD) of NR presents liquid-like, very narrow signals (full width at half height, FWHH, is less than 10 Hz). However,(More)
We have investigated the influence of the high centrifugal pressure caused by fast magic-angle spinning (MAS) on the molecular motion of styrene–butadiene rubbers (SBR) filled with SiO2 (SBR/Si composite) though solid-state magic-angle spinning nuclear magnetic Resonance (1H MAS NMR) measurements. Because the 1H–1H dipolar interaction of elastomers is weak(More)
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