Detection of a metallo-beta-lactamase (IMP-1) by fluorescent probes having dansyl and thiol groups

A fluorescent probe for the detection of a metallo-beta-lactamase (IMP-1), N-[2-(5-dimethylaminonaphthalen-1-ylsulfonylamino)ethyl]-3- mercaptopropionamide (Dansyl-C2SH), 1, was designed based on combining the inhibitory function of mercaptocarboxylate and a fluorophore. The binding of 1 to IMP-1 was investigated by fluorescence spectroscopy. Compound 1 can act as fluorescent probe for detecting IMP-1 selectively.     

Hydrometallation of 1-alkyl-3-trifluoromethyl propargyl alcohols

The hydrometallation of trifluoromethylated propargyl alcohol derivatives with metal hydride reagents proceeds smoothly to give cis- and trans-olefins on H₂O quenching. The halodemetallation of intermediate formed in the reaction process was also examined.     

Induced Fitting and Polarization of a Bromine Molecule in an Electrophilic Inorganic Molecular Cavity and Its Bromination Reactivity

Dodecavanadate, [V₁₂O₃₂]^4? (V12), possesses a 4.4 Å cavity entrance, and the cavity shows unique electrophilicity. Owing to the high polarizability, Br₂ was inserted into V12, inducing the inversion of one of the VO₅ square pyramids to form [V₁₂O₃₂(Br₂)]^4? (V12(Br2)). The inserted Br₂ molecule was polarized and showed a peak at 185 cm^?1 in the IR spectrum. The reaction of V12(Br2) and toluene yielded bromination of toluene at the ring, showing the electrophilicity of the inserted Br₂ molecule. Compound V12(Br2) also reacted with propane, n‐butane, and n‐pentane to give brominated alkanes. Bromination with V12(Br2) showed high selectivity for 3‐bromopentane (64 %) among the monobromopentane products and preferred threo isomer among 2‐,3‐dibromobutane and 2,3‐dibromopenane. The unique inorganic cavity traps Br₂ leading the polarization of the diatomic molecule. Owing to its new reaction field, the trapped Br₂ shows selective functionalization of alkanes.     

WIDE RANGE DETECTOR USING PARABOLIC CYLINDRICAL MIRROR FOR THz APPLICATIONS

A new, wide-band, high-speed and high-sensitivity THz detector has been developed. The prototype detector consists of a parabolic cylindrical mirror, a long wire antenna and a Schottky barrier diode. Direct detection measurements have shown a stable sensitivity of 150 ± 50 V/W for 1–2 THz without any adjustments. The long wire antenna was fixed at the focus of parabolic cylindrical mirror then it has been realized less operation steps, easy coupling to the external THz signals and a dramatic enhancement in the practicality of this system. The optically polished mirror and frosted surface one showed comparable sensitivities, thus easy polishing and less cost mirror fabrication can be applied for this system. The radiation pattern showed a maximum radiation angle of approximately 23° with its dominant main lobe, which was attributed to the wire antenna character and confirmed good agreements with classical antenna theory.     

Widely tunable terahertz-wave generation using an N-benzyl-2-methyl-4-nitroaniline crystal

Widely tunable terahertz (THz)-wave generation using difference frequency generation (DFG) in an organic N-benzyl-2-methyl-4-nitroaniline (BNA) crystal was demonstrated. To our knowledge, this is the first report of THz-wave generation by BNA DFG. Large, high-quality single crystals of BNA (phi 8 mm x 30 mm) were grown using the vertical Bridgman method. The nonlinear optical (NLO) coefficient d(33) of the BNA crystal is approximately 234 pm/V, which is the largest value reported for any yellow NLO material. The collinear phase-matching condition of the type-0 configuration is satisfied using a 0.7-1 microm band pump wavelength. We generated THz waves using an organic BNA crystal; the generation range is 0.1-15 THz.     

Efficient on-column conversion of IgG1 trisulfide linkages to native disulfides in tandem with Protein A affinity chromatography

Protein trisulfide linkages are generated by the post-translational insertion of a sulfur atom into a disulfide bond. Molecular heterogeneity was detected in a recombinant IgG₁ monoclonal antibody (mAb) and attributed to the presence of a protein trisulfide moiety. The predominant site of trisulfide modification was the bond between the heavy and light chains. The trisulfide was eliminated during purification of the IgG₁ mAb via a cysteine wash step incorporated into Protein A affinity column chromatography. Analysis of the cysteine-treated mAb by electrophoresis and peptide mapping indicated that the trisulfide linkages were efficiently converted to intact disulfide bonds (13% trisulfide decreased consistently to 1% or less) without disulfide scrambling or an increase in free sulfhydryls. The on-column trisulfide conversion caused no change in protein folding detectable by hydrogen/deuterium exchange or differential scanning calorimetry. Consistent with this, binding of the mAb to its antigen in vitro was insensitive to the presence of the trisulfide modification and to its removal by the on-column cysteine treatment. Similar, high efficiency trisulfide conversion was achieved for a second IgG₁ mAb using the column wash strategy (at least 7% trisulfide decreased to 1% or less). Therefore, trisulfide/disulfide heterogeneity can be eliminated from IgG₁ molecules via a convenient and inexpensive procedure compatible with routine Protein A affinity capture.