Publications by authors named "Takahiro Niwa"

Chicken egg white protein ovalbumin (OVA) undergoes a conversion to a more thermostable form by alkali treatment, which is assumed to be involved in the physiological functions of OVA. Ovalbumin-related protein X (OVAX), a chicken egg white protein, has 77% sequence similarity to OVA and binds to heparin. In this study, structure characteristics and heparin-binding affinity of alkali-treated OVAX were investigated.

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Pyrimidine-based diboron complexes bearing β-iminoenolate ligands and phenyl groups as bulky substituents on the boron atoms were synthesized as novel fluorescent dyes, and their fluorescence properties were investigated in solution and in the solid state. The diboron complexes with donor-π-acceptor structures showed positive solvatochromism in the fluorescence spectra. The cyano derivative exhibited the most dramatic redshift of the fluorescence maximum Fmax with increasing solvent polarity (from 551 nm in n-hexane to 710 nm in acetonitrile).

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Novel bisboron complexes of bidentate ligands consisting of 1,4-benzoquinone and two pyrrole rings were synthesized by using a simple two-step reaction. In solution, the bisboron complexes showed absorption maxima at ∼620 and 800 nm, which were attributed to the allowed S0 → S2 and forbidden S0 → S1 transitions, respectively. The bisboron complexes did not show any fluorescence, probably because of their highly symmetrical structure which forbids the S0 → S1 transition.

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