Imaging properties of optical scanning holography and an aberration compensation filter.

We propose a numerical technique that analyses the imaging properties of optical scanning holography (OSH) constructed using real optical components in a real optical alignment situation. Using the proposing technique, we analyze the aberrations and the vulnerability of the OSH about the optical alignment. After that, we propose a digital filter that compensates the aberrations of the OSH. Finally, we show that the digital filter removes the aberrations of an experimentally recorded OSH.

Selective tuning of activity in a multifunctional enzyme as revealed in the F21W mutant of dehaloperoxidase B from Amphitrite ornata.

Possessing both peroxidase and peroxygenase activities with a broad substrate profile that includes phenols, indoles, and pyrroles, the enzyme dehaloperoxidase (DHP) from Amphitrite ornata is a multifunctional catalytic hemoglobin that challenges many of the assumptions behind the well-established structure-function paradigm in hemoproteins. While previous studies have demonstrated that the F21W variant leads to attenuated peroxidase activity in DHP, here we have studied the impact of this mutation on peroxygenase activity to determine if it is possible to selectively tune DHP to favor one function over another. Biochemical assays with DHP B (F21W) revealed minimal decreases in peroxygenase activity of 1.2-2.1-fold as measured by 4-nitrophenol or 5-Br-indole substrate conversion, whereas the peroxidase activity catalytic efficiency for 2,4,6-trichlorophenol (TCP) was more than sevenfold decreased. Binding studies showed a 20-fold weaker affinity for 5-bromoindole (K d = 2960 ± 940 µM) in DHP B (F21W) compared to WT DHP B. Stopped-flow UV/visible studies and isotope labeling experiments together suggest that the F21W mutation neither significantly changes the nature of the catalytic intermediates, nor alters the mechanisms that have been established for peroxidase and peroxygenase activities in DHP. The X-ray crystal structure (1.96 Å; PDB 5VLX) of DHP B (F21W) revealed that the tryptophan blocks one of the two identified TCP binding sites, specifically TCPinterior, suggesting that the other site, TCPexterior, remains viable for binding peroxygenase substrates. Taken together, these studies demonstrate that blocking the TCPinterior binding site in DHP selectively favors peroxygenase activity at the expense of its peroxidase activity.

A highly selective quinoline-based fluorescent sensor for Zn(II).

A quinoline-based simple receptor (bis(2-quinolinylmethyl)benzylamine = 1) as a Zn(2+) selective fluorescent chemosensor showed a large fluorescent enhancement with a blue shift in the presence of Zn(2+) which is attributed to a chelation enhanced fluorescence (CHEF) effect with inhibition of a photoinduced electron transfer (PET) process of 1. In particular, this receptor could clearly distinguish Zn(2+) from Cd(2+). The binding mode of 1 and Zn(2+) was found to be a 1:1 and confirmed by Job plot, (1)H NMR titration and ESI-mass spectrometry analysis.

A cap-type Schiff base acting as a fluorescence sensor for zinc(II) and a colorimetric sensor for iron(II), copper(II), and zinc(II) in aqueous media.

A simple and low cost chemosensor is described. This sensor could simultaneously detect three biologically important metal ions through fluorogenic (Zn(2+)) and chromogenic (Fe(2+), Cu(2+), and Zn(2+)) methods in aqueous solution. The sensor could function as a "turn-on" fluorescence receptor only to Zn(2+) ions. In addition, the sensor could be successfully applied to the detection of intracellular Zn(2+). Meanwhile, the sensor displayed an obvious red color upon selective binding with Fe(2+). Therefore, the sensor could serve as a useful tool for the discrimination of Fe(2+) from Fe(3+) in aqueous media. Moreover, the sensor also showed color changes from yellow to colorless upon selective binding with Zn(2+) and Cu(2+), respectively. The detection limit of the sensor for Cu(2+) (1.5 µM) is far below the guidelines of the World Health Organization (30 µM) as the maximum allowable copper concentration in drinking water, and therefore it is capable of being a practical system for the monitoring of Cu(2+) concentrations in aqueous samples. These results provide a new approach for selectively recognizing the most important three trace elements in the human body simultaneously, for Zn(2+) by emission spectra and Fe(2+), Cu(2+), and Zn(2+) by the naked eye.

5-Carbamoyl-2-methyl-1-(2-methyl-benz-yl)pyridinium bromide.

In the title mol-ecular salt, C(15)H(17)N(2)O(+)·Br(-), the benzene and pyridinium rings form a dihedral angle of 83.0 (1)°. In the crystal, N-H⋯Br and N-H⋯O hydrogen bonds link the components into chains along [010]. These chains are linked by weak C-H⋯O and C-H⋯Br hydrogen bonds, forming a three-dimensional network.

3-Carbamoyl-1-(2-nitrobenzyl)pyridin-ium bromide.

In the title compound, C(13)H(12)N(3)O(3) (+)·Br(-), the benzene and pyridinium rings form a dihedral angle of 82.0 (1)°. In the crystal, N-H⋯Br and N-H⋯O hydrogen bonds link the components into chains along [001]. In addition, weak C-H⋯O and C-H⋯Br hydrogen bonds are observed.