Characterization of new oxovanadium(IV) complexes of saccharides

Oxovanadium(IV) complexes of the monosaccharides D- and L-arabinose, D-galactose, D-mannose, D-lyxose, D-xylose and the disaccharide maltose were obtained in aqueous solutions at pH 13. Their sodium salts were precipitated with absolute ethanol and characterized by UV-vis spectroscopy (absorption and reflectance), thermo-analytical (TG and DTA) data, magnetic susceptibility measurements and IR-spectroscopy. All the complexes were found to be mononuclear, possessing the VO2+ moiety. The IR spectra were analyzed and discussed in detail allowing one to determine the characteristics of the metal-to-ligand interactions.     

Metal complexes of carnosine

The ligand properties of carnosine are analyzed. The stoichiometry, stability constants, and structural and spectroscopic characteristics of its coordination compounds with transition and representative metal cations are discussed. Mixed ligand systems containing carnosine are also presented. The biological activity of some of these metallic complexes is briefly considered.     

Vanadium(V) complexes with salicylaldehyde semicarbazone derivatives bearing in vitro anti-tumor activity toward kidney tumor cells (TK-10): crystal structure of [VVO2(5-bromosalicylaldehyde semicarbazone)

As a contribution to the development of novel vanadium complexes with pharmacologically interesting moieties, new dioxovanadium(V) semicarbazone complexes with the formula cis-VO(2)L, where L=5-bromosalicylaldehyde semicarbazone and 2-hydroxynaphtalen-1-carboxaldehyde semicarbazone have been synthesized and characterized by (1)H and (13)C NMR, Raman and FTIR spectroscopies. Results were compared with those previously reported for other three analogous complexes of this series. The five complexes were tested in three different human tumor cell lines for bioactivity as potential anti-tumor agents, showing selective cytotoxicity on TK-10 cell line. Results showed that structural modifications on the semicarbazone moiety could have a significant effect on the anti-tumor activity of the vanadium complexes. In addition, the electrochemical behavior of all the complexes was studied. No apparent correlation could be demonstrated between reduction potentials of the complexes and their anti-tumor activities. The molecular structure of the novel [V(V)O(2)(5-bromosalicylaldehyde semicarbazone)] complex was solved by X-ray diffraction methods. The vanadium atom shows a distorted square pyramidal coordination sphere. The (VO(2))(+) cation is coordinated to a nearly planar (L)(-) anion acting as a tridentate ligand through both oxygen and one nitrogen atoms.     

Cloning, expression, and purification of a recombinant cold-adapted beta-galactosidase from antarctic bacterium Pseudoalteromonas sp. 22b

The gram-negative antarctic bacterium Pseudoalteromonas sp. 22b, isolated from the alimentary tract of krill Thyssanoessa macrura, synthesizes an intracellular cold-adapted beta-galactosidase. The gene encoding this beta-galactosidase has been PCR amplified, cloned, expressed in Escherichia coli, purified, and characterized. The enzyme is active as a homotetrameric protein, and each monomer consists of 1028 amino acid residues. The enzyme was purified to homogeneity (50% recovery of activity) by using the fast, two-step procedure, including affinity chromatography on PABTG-Sepharose. Enzymatic properties of the recombinant protein are identical to those of native Pseudoalteromonas sp. 22b beta-galactosidase. The enzyme is cold-adapted and at 10 degrees C retains 20% of maximum activity. The purified enzyme displayed maximum activity close to 40 degrees C and at pH of 6.0-8.0. PNPG was its preferred substrate (58% higher activity than against ONPG). The enzyme was particularly thermolabile, losing all activities within 10 min at 50 degrees C. The hydrolysis of lactose in a milk assay revealed that 90% of milk lactose was hydrolyzed during 6 h at 30 degrees C and during 28 h at 15 degrees C. Because of its attributes, the recombinant Pseudoalteromonas sp. 22b beta-galactosidase could be applied at refrigeration temperatures for production of lactose-reduced dairy products.     

Production and preliminary characteristics of polyclonal antibodies specific to SSTR2A and SSTR5 receptors in the pituitary gland

The increasing interest in somatostatin receptors (SSTR) is mainly due to their involvement in the regulation of hormone secretion and the role in somatostatin analogue treatment of patients with pituitary adenomas. The efficiency of this treatment is highly dependent on receptor expression in tissue which on the protein level requires specific anti-receptor antibodies for testing. In this paper we introduced the principles for the production of several polyclonal antibodies specific for C-terminal intracellular part or N-terminal extracellular part of SSTR2A and SSTR5 receptors. The antibodies were highly specific for peptides used for immunization of animals, had low cross-reaction activities for other SSTR2A and SSTR5 peptides and reacted with receptors on immunoblots and in immunohistochemistry. The final verification of the antibodies' specificity would allow us to perform the research concerning the structure and posttranslational modifications of SSTR and avoid dependency of commercial sources.     

Getting a GRIP on liprins

Excessive grooming behaviors, cleansing rituals, and self-mutilation are important features of a range of neuropsychiatric diseases including obsessive compulsive (OC)-spectrum disorders. In this issue of Neuron, Greer and Capecchi (2002) report that Hoxb8 mutant mice exhibit this behavioral phenotype. These Hoxb8 mutants will be valuable in exploring the genetics and pathophysiology of OC-spectrum disorders as well as strategies for their treatment.     

Tail-fiber attachement in bacteriophage T4D studied by quasielastic light scattering–band electrophoresis

Mixtures of bacteriophage T4D particles with up to six tail fibres attached were seprated and analyzed in a quasielastic light scattering-band electrophoresis apparatus. The electrophoretic mobilities and diffusion coefficients of the seprated bands were determined during the same experiment. Species differing in mobility by 0.05 × 10^?4 cm²/V sec were resolved. Henry's electropheresis theory for spheres indicates that each tail fiber contributes about 140 effective positive charges to the phage structure. Estimate of the charge using the permanent dipole moment and the electrophorectic mobility (Bontje et. al. (1977) Biopolymers 16 , 551–572) gives an effective charge of + 230 to ?250 per tail fiber. The charge distribution on the fiberless particles was estimated to be ?3380 on the head and ?290 on the tail if the dipole moment was assumed positive and ?1400 on the head and ?1000 on the tail for a negative dipole. Tail-fiber attachement does not proceed to completion in our invitro system, as substantial distributions as a function of tail-fiber input indicates the reaction is a random, noncooperative process.