Toward an Alternative Intrinsic Probe for Spectroscopic Characterization of a Protein

The intrinsic fluorescent amino acid tryptophan is the unanimous choice for the spectroscopic investigation of proteins. However, several complicacies in the interpretation of tryptophan fluorescence in a protein are inevitable and an alternative intrinsic protein probe is a longstanding demand. In this contribution, we report an electron-transfer reaction in a human transporter protein (HSA) cavity which causes the tryptophan residue (Trp214) to undergo chemical modification to form one of its metabolites kynurenine (Kyn214). Structural integrity upon modification of the native protein is confirmed by dynamic light scattering (DLS) as well as near and far circular dichroism (CD) spectroscopy. Femtosecond-resolved fluorescence transients of the modified protein describe the dynamics of solvent molecules in the protein cavity in both the native and denatured states. In order to establish general use of the probe, we have studied the dipolar interaction of Kyn214 with a surface-bound ligand (crystal violet, CV) of the protein. By using the sensitivity of FRET, we have determined the distance between Kyn214 (donor) and CV (acceptor). Our study is an attempt to explore an alternative intrinsic fluorescence probe for the spectroscopic investigation of a protein. In order to establish the efficacy of the modification technique we have converted the tryptophan residues of other proteins (bovine serum albumin, chymotrypsin and subtilisin Carlsberg) to kynurenine and confirmed their structural integrity. We have also shown that catalytic activity of the enzymes remains intact upon the modification

N-(6-Bromo­meth­yl-2-pyrid­yl)acetamide

The title acetamide compound, C8H9BrN2O, crystallizes with three crystallographically independent mol­ecules (A, B and C) in the asymmetric unit. In mol­ecule A, the mean plane through the acetamide unit is inclined at a dihedral angle of 4.40 (11)° with respect to the pyridine ring [10.31 (12) and 2.27 (11)°, respectively, for mol­ecules B and C]. In the crystal structure, mol­ecules are inter­connected into sheets parallel to the ac plane by N—H⋯O, C—H⋯Br, C—H⋯O and C—H⋯N hydrogen bonds. The structure is further stabilized by weak inter­molecular C—H⋯π inter­actions

A sustainable approach for synthesis of zinc oxide nanoparticle by Aloe barbadensis and its application in photocatalytic decolouration of commercial dyes.

Zinc oxide nanoparticles (ZnONPs) biosynthesis is gaining popularity since it is environmentally safe and can withstand a wide range of environmental conditions. The widely known medicinal herb Aloe barbadensis was employed to create ZnONPs in this work. XRD (X-Ray Diffraction), EDAX (Energy dispersive X-ray microanalysis), and TEM (Transmission Electron Microscopy) were also used to characterise the produced ZnONPs. In XRD, the produced ZnONPs revealed crystalline character, with an average size of 30 50 nm. TEM was used to determine spherical morphology. Under ultraviolet irradiation, the photocatalytic decolorization of Sudan IV, Crystal Violet (CV), and Acridine Orange (AO) by biogenic produced ZnONPs was studied. Using all three dyes (10-50 ppm) throughout a 4-hour incubation time, the produced ZnONPs showed 100% photocatalytic decolorization activity    &nbsp

Quinoxaline-2-carbonitrile

In the title compound, C9H5N3, the quinoxaline ring is essentially planar, with a maximum deviation of 0.012 (1) Å. Short inter­molecular distances between the centroids of the 2,3-dihydro­pyrazine and benzene rings [3.6490 (5) Å] indicate the existence of π⋯π inter­actions. In the crystal packing, the mol­ecules are linked via two pairs of inter­molecular C—H⋯N inter­actions, forming R 2 2 (8) and R 2 2 (10) ring motifs; these mol­ecules are further linked into a two-dimensional network parallel to (1 0 2) via another C–H⋯N inter­action

2,7-Dimethyl-1,8-naphthyridine

The asymmetric unit of the title compound, C10H10N2, contains one half-mol­ecule with the two shared C atoms lying on a twofold rotation axis. The 1,8-naphthyridine is almost planar with a dihedral angle of 0.42 (3)° between the fused pyridine rings. In the crystal, mol­ecules are linked into infinite chains along the c axis by inter­molecular C—H⋯N hydrogen bonds, generating R 2 2(8) ring motifs. In addition, the crystal structure is further stabilized by C—H⋯π inter­actions

N-(6-{2-[6-(2,2-Dimethyl­propanamido)-2-pyrid­yl]eth­yl}-2-pyrid­yl)-2,2-dimethyl­propanamide

The title compound, C22H30N4O2, lies about a crystallographic inversion center. The whole mol­ecule is disordered over two positions with a refined occupancy ratio of 0.636 (10):0.364 (10). The pyridine rings are approximately planar, with maximum deviations of 0.033 (10) and 0.063 (17) Å for the major and minor components, respectively. The mean planes of the pyridine rings form dihedral angles of 17 (2)° in the major component and 18 (2)° in the minor component with the respective formamide groups attached to them. In the crystal packing, inter­molecular N—H⋯O and C—H⋯O hydrogen bonds link the mol­ecules into two-dimensional networks parallel to the ab plane

2-(Pyrene-1-yl)-1,3-dithiane

In the title compound, C20H16S2, the pyrene ring is planar [maximum deviation 0.0144 (15) Å] and the dithiane ring adopts a chair conformation. The crystal packing is stabilized by C—H⋯π inter­actions. An intra­molecular C—H⋯S hydrogen bond generates an S(5) ring motif

Effect of shell thickness on exciton and biexciton binding energy of a ZnSe/ZnS core/shell quantum dot

The exciton and biexciton binding energy have been studied for a ZnSe/ZnS core/shell quantum dot using WKB (Wentzel-Kramers-Brillouin) approximation. The exciton binding energy increases for small shell thickness and for large thickness, the binding energy again starts decreasing. A similar result is obtained for biexcitons where for thicker shells, the biexciton attains antibonding.Comment: 5 Figure

Effect of Tephrosia purpurea roots extracts on acetic acid induced colitis in mice

Tephrosia purpurea L. (Leguminosae), commonly known as Unhali in Marathi is a copiously branched perennial herb. Traditionally the roots of this plant are used in the treatment of ulcer and colic pain. So the present work was undertaken to validate its use in the treatment of ulcerative colitis by using suitable scientific methods. Shade dried and coarsely powdered roots were subjected to successive extraction with ethanol and water. The dried extracts (100 and 200 mg/kg) were screened for ulcerative colitis using the method acetic acid induced ulcerative colitis in mice. Macroscopical study of the colon, level of myeloperoxidase in colon and histopathology of the colon tissue were studied for the assessment of the activity. Results showed that aqueous extract was significantly effective in the treatment of ulcerative colitis at dose of 200 mg/kg. It can be concluded that the polar constituents of T. purpurea L. may be useful in the treatment of ulcerative colitis.Colegio de Farmacéuticos de la Provincia de Buenos Aire