Development of a fluorescence peptide chip for the detection of caspase activity

Proteases play a key role in cell functions, and it is very important to monitor their activities for drug screening and diagnosis of diseases. In the present study, a new class of fluorescence probe, into which a fluorophore and a quencher have been introduced, was developed and applied to the on-chip detection of caspase-3 activity. This probe is non fluorescent in the absence of caspase-3. However, when it is treated with active caspase-3, the fluorescence intensity increases dependent on the caspase-3 activity due to the cleavage of the quencher-containing moiety on a glass slide. This caspase-dependent increase in the fluorescence intensity was also detected when the glass slide immobilizing the probe peptide was treated with cell lysate stimulated by staurosporine (STP), which is an apoptosis-inducing agent. On the other hand, such an increase was not detected in the case of control cell lysate without STP-stimulation. The developed system is a rapid and sensitive method and is useful for the direct measurement of protease activity on a glass array.     

Practical access to the polymer incarcerated platinum (PI Pt) catalyst and its application to hydrogenation

Polymer incarcerated platinum catalysts (PI Pt) were conveniently prepared from PtCl(2)(COD) or H(2)PtCl(6).6H(2)O and styrene copolymers via reduction of the Pt sources with triethylamine, coacervation, and cross-linking. The Pt catalysts have been successfully applied to catalytic hydrogenation including saturation of heterocyclic compounds.     

Practical preparation method of polymer-incarcerated (PI) palladium catalysts using Pd(II) salts

[reaction: see text]. Polymer-incarcerated (PI) palladium catalyst was practically prepared from inexpensive Pd(II) salts and a polystyrene-based copolymer under reducing conditions. Remarkable effects of alkali metal salts on the palladium loading were observed. PI Pd thus prepared showed high catalytic activity in Mizoroki-Heck reactions and Suzuki-Miyaura couplings with a range of substrates including an aryl chloride. In all cases, the Pd catalyst was recovered quantitatively without leaching, and reused several times without significant loss of activity.     

2,3-disubstituted benzofuran and indole by copper-mediated C-C bond extension reaction of 3-zinciobenzoheterole

[reaction: see text] A metalative 5-endo-dig cyclization reaction of 2-ynylphenoles or anilines effected by BuLi and ZnCl(2) produces 3-zinciobenzoheteroles in excellent yield. These intermediates have been transmetalated to the corresponding cuprates and allowed to react with electrophiles to produce a variety of 2,3-disubstituted benzofurans and indoles.     

Two-dimensional Monte Carlo simulations of a colloidal dispersion composed of rod-like ferromagnetic particles in the absence of an applied magnetic field

Influences of the magnetic interaction between particles and the aspect ratio of particles on aggregate structures in a colloidal dispersion composed of rod-like ferromagnetic particles were investigated by means of the cluster-moving Monte Carlo method. The internal structures of the aggregates obtained in simulations were analyzed in terms of the number density distribution of the clusters and radial distribution functions. The results show that as the magnetic interaction between particles increases, many small clusters such as anti-parallel particle pairs, raft-like clusters, and small loop-like clusters are formed; these gather to form larger aggregates. In the case of a relatively strong magnetic interaction between particles, solid-like rectangular clusters are formed when the aspect ratio is approximately 2, since the suitable distance between magnetic charges enables particles to form a fundamental structure of two normal anti-parallel particle pairs. As the aspect ratio increases beyond 2, many more stable raft-like clusters are formed, since the increase in distance between magnetic charges makes the two normal anti-parallel particle pair structures unstable. For a significantly larger aspect ratio, large network microstructures are produced by the formation of many chain-like and loop-like structures.     

Palladium-catalyzed selective 2,3-diarylation of alpha,alpha-disubstituted 3-thiophenemethanols via cleavage of C-H and C-C bonds

Alpha,alpha-disubstituted 3-thiophenemethanols undergo selective diarylation accompanied by cleavage of the C-H and C-C bonds of the 2- and 3-positions, respectively, upon treatment with aryl bromides in the presence of a palladium catalyst to give the corresponding 2,3-diarylthiophenes in good yields.     

The braid index is not additive for the connected sum of 2-knots

Any -dimensional knot can be presented in a braid form, and its braid index, , is defined. For the connected sum of -knots and , it is easily seen that holds. Birman and Menasco proved that the braid index (minus one) is additive for the connected sum of -dimensional knots; the equality holds for -knots. We prove that the equality does not hold for -knots unless or is a trivial -knot. We also prove that the -knot obtained from a granny knot by Artin's spinning is of braid index , and there are infinitely many -knots of braid index .

     

Rheological properties and particle behaviors of a nondilute colloidal dispersion composed of ferromagnetic spherocylinder particles subjected to a simple shear flow: analysis by means of mean-field approximation for the two typical external magnetic field directions

We have analyzed the orientational distributions and rheological properties of a nondilute colloidal dispersion composed of ferromagnetic spherocylinder particles subjected to a simple shear flow. In order to understand the effects of the magnetic interactions between the particles, we have applied the mean-field theory to a nondilute colloidal dispersion for the two typical external magnetic field directions, that is, the direction parallel to the shear flow and the direction parallel to the angular velocity vector of the shear flow. The main results are summarized as follows. The particle-particle interactions suppress the Brownian motion of the particles and, therefore, make the particles incline toward the same direction. For the magnetic direction parallel to the shear flow, the influence of the particle-particle interactions makes the peak of the orientational distribution sharper and higher. The viscosity generally increases as the interactions between particles become stronger in the case where the effects of the shear flow and magnetic field are relatively small. For the magnetic direction parallel to the angular velocity vector of the shear flow, the influence of the particle-particle interactions on the orientational distribution appears significantly, when the influences of the shear flow and magnetic field are not so strong that the particles can be aligned sufficiently to form stable chainlike clusters in a certain direction.     

Stereospecific cross-coupling between alkenylboronates and alkyl halides catalyzed by iron-bisphosphine complexes

A stereospecific and high-yielding cross-coupling reaction between alkenylboron reagents and alkyl halides is described. The reaction has been achieved by using well-defined iron-bisphosphine complexes such as 1b FeCl(2)(3,5-t-Bu(2)-SciOPP), which was recently developed by the authors' group. Various nonactivated alkyl bromides and chlorides possessing a base/nucleophile-sensitive functional group can participate in the cross-coupling, demonstrating its utility for stereoselective synthesis of functional molecules bearing a carbon-carbon double bond.