Shohei Tashiro 교수

The single binding pocket of a self-assembled Pd6L4 coordination cage recognizes oligopeptides in a highly sequence-selective fashion. In particular, the Trp-Trp-Ala sequence is strongly bound by the cavity (Ka >/=106 M-1). Tripeptides possessing the same residues but in different sequences (i.e., Trp-Ala-Trp and Ala-Trp-Trp) show much poorer affinity. Even singly mutated tripeptides with aromatic-aromatic-aliphatic sequences of the residues (e.g., Trp-Trp-Gly and Trp-Tyr-Ala) are not recognized

Crystal engineering: A dodecapyridine ligand and six PdII ions self-assemble to give a mono-end-capped coordination tube that has significant stability, but is converted into a double open tube through crystallization. Once formed, there is no route back to the capped tube (see picture). Despite the labile nature of PdII–pyridine coordination bonds, both structures are not in a rapid equilibrium and are, therefore, kinetically trapped during self-assembly. Supporting information for this article

Molecular recognition is one of the fundamental events in biological systems, as typified by enzymes that enable highly efficient and selective catalytic reactions through precise recognition of substrate(s) and cofactor(s) in the binding pockets. Chemists therefore have long been inspired by such excellent molecular systems to develop various synthetic receptors with well-defined binding sites. Their effort is currently being devoted to the construction of not only molecular receptors but also

An Ac-Ala-Ala-Ala-NH2 tripeptide was folded into a beta-turn structure even in water through hydrophobic binding by a self-assembled porphyrin cage. The turn conformation of the bound peptide was fully assigned from NOESY measurements and was strongly supported by molecular dynamics simulation. Single mutation experiments and molecular modeling also suggested that CH-pi interactions between methyl groups of Ala residues and porphyrin ligands were important for the stabilization of the turn confo

In a twist: Encapsulation of a nine-residue peptide (Trp-Ala-Glu-Ala-Ala-Ala-Glu-Ala-Trp) within a bowl-shaped coordination host in water induces and stabilizes the α-helical conformation. The α-helical peptide is recognized through two types of host–guest interactions: a hydrophobic interaction with both terminal Trp residues and electrostatic interactions between the Glu residues and the high positive charge of the host (12+). Supporting information for this article is available on the WWW und

Hollow nanostructures for the functional assembly of chemical groups with inner surface geometry and regulable stoichiometry enable steric design of interior reaction centers. Herein we report a metal-macrocycle framework (MMF) that forms single-crystalline nanochannels with five distinct enantiomeric pairs of guest binding pockets. During crystal-soaking experiments, the MMF crystals can encapsulate aromatic molecules with high site selectivity. First, constitutional isomers of dibromobenzene a

Kein Weg zurück: Aus einem Dodecapyridin-Liganden und sechs PdII-Ionen bildet sich ein stabiler Komplex in Form einer einseitig geschlossenen Röhre. Dieser wandelt sich während der Kristallisation in ein beidseitig geöffnetes Dimer um (siehe Bild). Trotz der labilen Koordination der Pyridinliganden an die PdII-Zentren liegen die beiden Strukturen nicht im Gleichgewicht vor: Das Dimer entsteht irreversibel als Folge der Selbstorganisation.

The myb gene family has three members, c-myb, A-myb and B-myb. We have examined the trans-activating capacity of the B-myb gene product (B-Myb) in various types of cells. B-Myb functions as a transcriptional activator in CV-1 and HeLa cells, but not in NIH3T3 cells, indicating that B-Myb is a cell type-specific transcriptional activator. Deletion analyses of B-Myb have demonstrated that the region conserved between three members of the myb gene family (CR for conserved region) is necessary for t

A dimeric capsule of coordination bowl 1 encapsulated a nine-residue peptide (Trp-Ala-Glu-Ala-Ala-Ala-Glu-Ala-Trp; 2) within the large hydrophobic cavity in water, and stabilized the alpha-helical conformation of bound 2. An NMR titration experiment revealed that monomeric bowl 1 recognized two Trp residues at the both terminals of 2 through 1/2 = 1:1 to 2:1 complexation. The 1:1 and 2:1 species exist in equilibrium even in the presence of excess 1. It was found that the formation of the 2:1 com

1. By using chromodacryorrhea, the phenomenon of the shedding of bloody tears by rats, as a criterion, acetylcholine can be detected in as small amount as 0.2 γ. 2. Since there are 4 ranges of minimal dosages detectable with this phenomenon, from 2 mg to 0.2 γ, depending on the mode of injection and treatment, this same criterion can be used for a wide range of concentration of acetylcholine with accuracy.

Abstract Porous crystals such as metal–organic framework (MOF), porous coordination polymer (PCP), and porous organic crystals have shown promise as solid materials in terms of their great potentials for catalysis, separation and refinement techniques, environmental protection, nanoengineering, and pharmaceutical applications. Here we discuss cavity-assembled porous solids (CAPSs) formed as the result of self-assembly of macrocycles or cage compounds possessing well-defined binding cavities for

Porous crystals are excellent materials with potential spatial functions through molecular encapsulation within the pores. Co-encapsulation of multiple different molecules further expands their usability and designability. Herein we report the simultaneous arrangement of up to three different guest molecules, TTF (tetrathiafulvalene), ferrocene, and fluorene, on the pore surfaces of a porous crystalline metal-macrocycle framework (MMF). The position and orientation of adsorbed molecules arranged

The optically active cobalt(III) complex with chiral cyclen, (2S,5S,8S,11S)-2,5,8,11-tetraethyl-1,4,7,10-tetraazacyclododecane, preferentially binds to D-phenylglycine (D-Phg) or D-t-leucine (D-t-Leu) rather than L-Phg or L-t-Leu, respectively, with 20% de in dimethyl sulfoxide at 293 K. Comparative studies on the crystal structures of cobalt(III) complexes with d-Phg and l-Phg revealed that the diastereoselectivity is due to the difference in the steric hindrance that should occur between the a

The cleavage of CC bonds in π-conjugated systems is an important method for controlling their shape and coplanarity. An efficient way for the cleavage of an aromatic CC bond in a typical buckybowl corannulene skeleton is reported. The reaction of 2-pyridylcorannulene with a catalytic amount of IrCl3 ⋅n H2 O in ethylene glycol at 250 °C resulted in a structural transformation from the curved corannulene skeleton to a strain-free flat benzo[ghi]fluoranthene skeleton through a site-selective CC

Porous crystals have great potential to exert space-specific functions such as multipoint molecular recognition. In order to rationally enhance the porous function, it is necessary to precisely control molecular recognition event in the pores. Hydrogen bonding is an effective tool for controlling molecular recognition. However, multiple hydrogen bonds, which are essentially the origin of high complementarity and specificity, remain difficult to innovate in porous crystals in an intelligent way.