These authors contributed equally to this work.

A two-dimensional, glycopolymer-immobilized, photonic crystal (PhC) biosensor was developed for the detection of proteins.

We developed a novel protease assay device using nanoimprinted two-dimensional photonic crystal (2D-PhC) for the first time. 2D-PhC exhibits a characteristic reflection, and its intensity is strongly affected by small changes in refractive index (RI) of the 2D-PhC surface. In this study, protease substrate-immobilized 2D-PhC was newly developed in order to measure the protease activity, and the simple and selective detection of protease activity using 2D-PhC was successfully performed.

The use of naked unmodified small interfering RNA (N-siRNA) without vector has previously been investigated as a pulmonary therapy. However, little is known regarding stabilities and aerodynamic particle sizes of N-siRNA-containing droplets; nebulizers have not yet been optimized for N-siRNA solutions. Thus, in this study, we investigated the feasibility of inhaled N-siRNA solutions for pulmonary therapy using nebulization. Various nebulizers and N-siRNA concentrations were assessed in terms of siRNA integrity after nebulization, and inhalation properties including aerodynamic particle size were examined. In comparison with ultrasonic-, air-jet-, and vibrating-mesh nebulizers, N-siRNA integrity was not affected by nebulization. Thus, in further experiments, performances of N-siRNA aerosols with different nebulizers and N-siRNA concentrations were evaluated and screened using an aerodynamic particle sizer (APS) which employed the time-of-flight principle or a cascade impactor. Mean mass aerodynamic diameters of N-siRNA-containing droplets from vibrating-mesh nebulizers tended to decrease with increasing N-siRNA concentrations, reflecting the influence of N-siRNA solutions on surface tension, as indicated by contact angles. These data indicate the utility of APS instruments for investigating the nebulized characteristics of expensive drugs including siRNAs and may facilitate the development of N-siRNA inhalation formulations.Key words small interfering RNA (siRNA); vibrating-mesh nebulizer; aerodynamic particle size; surface tension; contact angle Small interfering RNA (siRNA) has a great therapeutic potential as a tool for the post-transcriptional silencing of target gene expression. 1) Recently, the field of siRNA delivery has rapidly progressed, and the local pulmonary delivery of siRNA has been investigated for various lung diseases. 2,3)Inhalation is the most popular noninvasive method for delivering therapeutic siRNA agents to the lungs 4); local siRNA inhalation therapy reduced virus titers in the lung and attenuated local pulmonary chemokine production after acute lung injury and infection.5,6) However, naked (unmodified) siRNA (N-siRNA) is susceptible to nuclease degradation; siRNA delivery systems facilitating gene silencing efficiency, including those using cationic materials, can have cytotoxic effects. N-siRNA has been delivered with some success to the lung, although systemic delivery of N-siRNA generally fails to produce significant gene silencing effects.3,7) N-siRNA lacks delivery vectors that produce toxicity and inflammation; thus, N-siRNA formulation for pulmonary delivery offers advantages for safety and simplicity. However, few developments of N-siRNA formulations have been reported. Direct pulmonary N-siRNA delivery has been achieved in humans following the inhalation of aerosols generated by inhalers or nebulizers. Three types of inhalation devices are currently available for pulmonary drug delivery, including metered dose inhalers, dry powder inhalers, and nebulizers. Liquid nebulization e...

Native N,N 0 -diacetylchitobiose deacetylase from Pyrococcus furiosus (Pf-Dac) and its selenomethionine derivative (Se-Pf-Dac) were crystallized and analyzed in the presence and absence of cadmium ion. The four crystal structures fell into three different crystal-packing groups, with the cadmium-free Pf-Dac and Se-Pf-Dac belonging to the same space group, with homologous unit-cell parameters. The crystal structures in the presence of cadmium contained distorted octahedral cadmium complexes coordinated by three chlorides, two O atoms and an S or Se atom from the N-terminal methionine or selenomethionine, respectively. The N-terminal cadmium complex was involved in crystal contacts between symmetry-related molecules through hydrogen bonding to the N-termini. While all six N-termini of Se-Pf-Dac were involved in cadmiumcomplex formation, only two of the Pf-Dac N-termini participated in complex formation in the Cd-containing crystal, resulting in different crystal forms. These differences are discussed in light of the higher stability of the Cd-Se bond than the Cd-S bond. This work provides an example of the contribution of cadmium towards determining protein crystal quality and packing depending on the use of the native protein or the selenomethionine derivative.

N,N′-diacetylchitobiose deacetylase (Dac) is involved in the archaea-specific chitinolytic pathway. In order to develop a structure-based understanding of the chitinolytic pathway in hyperthermophilic Pyrococcus species, we performed crystallographic studies on Dacs from P. horikoshii (Ph-Dac) and P. furiosus (Pf-Dac). Neither Ph-Dac nor Pf-Dac was expressed in the soluble fraction of Escherichia coli harboring the expression plasmid. However, insertion of the target genes into the chromosome of E. coli yielded the soluble recombinant protein. The purified Pyrococcus Dacs were thermostable up to 950C. The crystal structures of Ph-Dac and Pf-Dac were determined at resolutions of 2.0 Å and 1.54 Å, respectively. The Pyrococcus Dac forms a hexamer comprised of two trimers. These Dacs are characterized by an intermolecular cleft, which is formed by two polypeptides in the trimeric assembly. In Ph-Dac, catalytic zinc situated at the end of the cleft is coordinated by three side chain ligands from His44, Asp47, and His155, and by a phosphate ion derived from the crystallization reservoir solution. We considered that the bound phosphate mimicked the tetrahedral oxyanion, which is an intermediate of hydrolysis of the N-acetyl group, and proposed an appropriate reaction mechanism. In the proposed mechanism, the Nε atom of His264 (from the adjacent polypeptide in the Ph-Dac sequence) is directly involved in the stabilization of the oxyanion intermediate. These factors give the archaeal Dacs unprecedented active site architecture as a zinc-dependent deacetylase.

Helical amphipathic peptides containing cationic and hydrophobic amino acid residues can possess potent antimicrobial activity against both Gram-positive and Gramnegative bacteria. In this study, several amphipathic peptides with enhanced helical structures containing nonproteinogenic amino acids were designed, and the relationships between the antimicrobial activity, hemolytic activity, and cytotoxicity were evaluated. In particular, the effect on the antimicrobial activity and cytotoxicity of the number and position of stapling structures introduced into the sequence was investigated. Peptide stp1 containing α,α-disubstituted amino acids showed potent antimicrobial activity against multidrug-resistant bacteria (MDRP, SP45, and Staphylococcus aureus) without causing appreciable hemolytic activity or cytotoxicity. The cytotoxicity was found to be somewhat correlated to the hydrophobicity of the peptides.