Tateaki Wakamiya

How the π Conjugation Length Affects the Fluorescence Emission Efficiency

How the pi conjugation length affects the fluorescence emission efficiency is elucidated by examination of the theoretical and experimental relationship between absolute quantum yield (Phi(f)) and magnitude (Api) of the pi conjugation length in the excited singlet state, which provides a novel concept for molecular design for highly fluorescent organic compounds. As a tool to predict Phi(f) from a structural model, (nu(a) - nu(f))1/2 x a3/2 (nu(a): wavenumber of absorption maximum, nu(f): wavenumber of emission maximum, a: molecular radius) could be used instead of Api. The concept should be valuable for potential applications to (1) examination of an excited singlet state structure (for example, coplanarity of excited-state molecules) and (2) molecular design of novel materials, in which the excited singlet state plays an important role, such as highly efficient fluorophores, electroluminescent materials, photoconducting materials, and nonlinear optical materials. A remarkably intense green fluorophore (Phi(f) 0.88, log epsilon 4.72, lambda(em) 527 nm) is created based on this concept, which is of great interest in relation to a green fluorescent protein (Topaz, T203Y type, Phi(f) 0.60, log epsilon 4.98, lambda(em) 527 nm).

The structure of ancovenin, a new peptide inhibitor of angiotensin I converting enzyme

Abstract The structure of ancovenin, a new peptide inhibitor of angiotensin I converting enzyme, was determined to be a unique tricyclic peptide which comprises sixteen amino acid residues including dehydroalanine and three sulfide amino acids as unusual components.

Total synthesis of peptide antibiotic nisin

Abstract Total synthesis of a lanthionine peptide nisin was successfully achieved for the first time by application of new methods for preparations of dehydroalanine and lanthionine moieties, resulting in a confirmation of the proposed structure.

Synthesis of a new neurotoxin NSTX-3 of Papua New Guinean spider

Abstract A new spider toxin NSTX-3 was chemically synthesized for confirmation of the proposed structure and use in the investigation of neuroscience.

Synthesis and stereochemistry of carnosadine, a new cyclopropyl amino acid from red alga Grateloupia carnosa

Abstract Optically active carnosadine, a new cyclopropyl amino acid from red alga Grateloupia carnosa , was synthesized and its absolute structure was determined.

Simple and efficient syntheses of Boc- and Fmoc-protected 4(R)- and 4(S)-fluoroproline solely from 4(R)-hydroxyproline

Abstract As building blocks of collagen model peptides, Boc- and Fmoc-protected 4(R)- and 4(S)-fluoroproline, which will be widely used in peptide synthesis including solid-phase strategy, were synthesized from the readily available 4(R)-hydroxyproline in higher yield than with conventional methods. To establish the stereospecificity of the Mitsunobu reaction and the subsequent fluorination that were presumed to cause the inversion of configuration at the C-4 position of a proline derivative, the absolute configuration of one of the key products, Boc-4(S)-fluoroproline, was determined by X-ray crystallography.

Total synthesis of capreomycin

Abstract Total syntheses have been achieved of capreomycin IA and IB according to our newly proposed structures. The β-lysine residue in the branch was introduced to the cyclic peptide moiety which was prepared by cyclization of the corresponding pentapeptide. Deprotection followed by conversion of β,β-diethoxyalanine residue to β-ureidodehydroalanine residue afforded the desired products, which were identical with natural capreomycins in all respects.

Adsorptive-mediated endocytosis of a basic peptide in enterocyte-like Caco-2 cells

The internalization of a basic peptide, 001-C8 [H-MeTyr-Arg-MeArg-D-Leu-NH(CH2)8NH2], into enterocyte-like Caco-2 cells was evaluated. Internalization of 125I-labeled 001-C8 (125I-001-C8) increased time dependently and reached steady state at 60 min. The steady-state internalization of 125I-001-C8 (7.24 +/- 0. 41 microl/mg protein) was temperature and concentration dependent and was significantly decreased by dansylcadaverine (500 microM), protamine (1 mM), poly-L-lysine (1 mM), E-2078 (1 mM), and ebiratide (1 mM), whereas poly-L-glutamic acid (1 mM), tyrosine (1 mM), and glycylglycine (25 mM) were not inhibitory. Predigestion of acid mucopolysaccharides by heparinase I, heparitinase, and chondroitinase ABC also decreased the internalization. The maximal internalization, the half-saturation constant, and the nonsaturable internalization of 125I-001-C8 were 1.13 +/- 0.23 pmol/mg protein, 0. 47 +/- 0.43 microM, and 3.13 +/- 0.19 microl/mg protein, respectively. Confocal microscopy also indicated the internalization of fluorescence-derived 001-C8 [001-C8-4-nitrobenz-2-oxa-1,3-diazole (001-C8-NBD)]. Granular staining seen within the cell, excluding nuclei, indicated the sequestration of 001-C8-NBD within endocytotic vesicles. Dansylcadaverine and protamine strongly decreased the granular distribution of 001-C8-NBD within the cell. These results demonstrate that 001-C8 is taken up by Caco-2 cells via adsorptive-mediated endocytosis.The internalization of a basic peptide, 001-C8 [H-MeTyr-Arg-MeArg-d-Leu-NH(CH2)8NH2], into enterocyte-like Caco-2 cells was evaluated. Internalization of125I-labeled 001-C8 (125I-001-C8) increased time dependently and reached steady state at 60 min. The steady-state internalization of 125I-001-C8 (7.24 ± 0.41 μl/mg protein) was temperature and concentration dependent and was significantly decreased by dansylcadaverine (500 μM), protamine (1 mM), poly-l-lysine (1 mM), E-2078 (1 mM), and ebiratide (1 mM), whereas poly-l-glutamic acid (1 mM), tyrosine (1 mM), and glycylglycine (25 mM) were not inhibitory. Predigestion of acid mucopolysaccharides by heparinase I, heparitinase, and chondroitinase ABC also decreased the internalization. The maximal internalization, the half-saturation constant, and the nonsaturable internalization of125I-001-C8 were 1.13 ± 0.23 pmol/mg protein, 0.47 ± 0.43 μM, and 3.13 ± 0.19 μl/mg protein, respectively. Confocal microscopy also indicated the internalization of fluorescence-derived 001-C8 [001-C8-4-nitrobenz-2-oxa-1,3-diazole (001-C8-NBD)]. Granular staining seen within the cell, excluding nuclei, indicated the sequestration of 001-C8-NBD within endocytotic vesicles. Dansylcadaverine and protamine strongly decreased the granular distribution of 001-C8-NBD within the cell. These results demonstrate that 001-C8 is taken up by Caco-2 cells via adsorptive-mediated endocytosis.

Lanthiopeptin, a new peptide effective against herpes simplex virus: Structural determination and comparison with Ro 09-0198, an immunopotentiating peptide

Abstract The structure of lanthiopeptin, a new lanthionine peptide effective against Herpes virus, was newly determined. It has a unique tetracyclic sequence which is very similar to but different from the proposed structure for Ro 09-0198. However, Ro 09-0198 was found to be quite the same compound as lanthiopeptin in all respects.

Synthesis of bulgecinine: a new amino acid in bulgecins☆

Abstract Bulgecinine, a new proline type amino acid in bulgecins, was synthesized stereospecifically by use of D -glucose as a chiral precursor.