Optical properties of ovalbumin in 0.130-2.50 microm spectral region

In our continuing series of measurements of the complex index of refraction for representative samples of biological materials, we measured ovalbumin (egg albumin) over the spectral region from 0.130 (76,923 cm(-1)) to 2.50 microm (4000 cm(-1)). Films of ovalbumin suitable for optical analyses were prepared and measured in addition to solutions of ovalbumin in water. We show several examples of how the methods used in this study produced accurate results for this complex and difficult to measure material. The present work is applicable to quantitative optical studies involving ovalbumin and other serpin proteins, as well as the study of proteinaceous toxins.     

Lipase-catalyzed production of a bioactive fatty amide derivative of 7,10-dihydroxy-8(E)-octadecenoic acid

Enzymatic syntheses of fatty amides are of considerable interest due to their wide ranging industrial applications in detergents, shampoo, cosmetics and surfactant formulations. Amidation reaction of Candida antarctica lipase B (CALB) was investigated for direct amidation of carboxylic acid in organic solvent. CALB-mediated production of a novel secondary amide was carried out by reacting the hydroxy oleic acid derivative, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD), with N-methylethanol amine in organic solvent medium. A single, new product peak corresponding to the secondary amide of DOD (D2AM) was detected by high-performance liquid chromatography and thin-layer chromatography. The production of D2AM was achieved in high yields (95%) after 72 h at 50 degrees C in a CALB-catalyzed reaction that contained 100 IU enzyme activity, 50 mM DOD, and 100 mM N-methylethanol amine in isoamyl alcohol. The new fatty amide D2AM displayed potent antimicrobial activity towards Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Proteus vulgaris and Klebsiella pneumonae). D2AM also exhibited antioxidative activity by its alpha,alpha-diphenyl-beta-picryl-hydrazyl (DPPH) radicals scavenging effects.     

Revealing monsoonal variability of the last 2,500 years over India using sedimentological and foraminiferal proxies

A 2-m-long, shallow-water sediment core, representing the last 2,500 years, collected from the tropical Arabian Sea from the inner shelf (22 m water depth) off Karwar, near the mouth of the Kali River, has been studied for sedimentological proxies (granulometry) and foraminiferal tracers of paleomonsoons. The results suggest a considerable decrease in the intensity of monsoons approximately around 2,000 years BP which is followed by an increase in the intensity of the precipitation around 1,000 years BP. The signals of similar climatic conditions around 2,000 years BP and around 1,000 years BP have also been recorded from other geographically distinct localities.     

Dimeric beta-turn peptidomimetics as ligands for the neurotrophin receptor TrkC

Twelve dimeric peptidomimetics 1 were prepared via a divergent-convergent strategy. These peptidomimetics incorporated the same amino acids as i +1 and i + 2 residues in key beta-turns of the neurotrophin NT-3. Cytosensor microphysiometry was used to gauge the effects of the dimers 1 on cells that overexpress the NT-3 receptor, TrkC. Increases in extracellular acidification rates were observed for some monomers 3, but the active dimers gave greater effects.     

Synthesis,opioid receptor binding,and functional activity of 5'-substituted 17-cyclopropylmethylpyrido[2',3':6,7]morphinans

A series of naltrexone-derived pyridomorphinans possessing various substituents at the 5'-position on the pyridine ring were synthesized and evaluated for opioid receptor binding in rodent brain membranes and functional activity in smooth muscle preparations. While the introduction of aromatic 1-pyrrolyl group (6h) improved the delta affinity and delta antagonist potency of the parent compound (3), the introduction of guanidine group (6i) transformed it to a kappa selective ligand in opioid receptor binding and [35S]GTP-gamma-S functional assays.     

Analysis of the Shewanella oneidensis proteome by two-dimensional gel electrophoresis under nondenaturing conditions

Proteomes are dynamic, i.e., the protein components of living cells change in response to various stimuli. Protein changes can involve shifts in the abundance of protein components, in the interactions of protein components, and in the activity of protein components. Two-dimensional gel electrophoresis (2-DE) coupled with peptide mass spectrometry is useful for the analysis of relative protein abundance, but the denaturing conditions of classical 2-DE do not allow analysis of protein interactions or protein function. We have developed a nondenaturing 2-DE method that allows analysis of protein interactions and protein functions, as demonstrated in our analysis of the cytosol and crude membrane fractions of the facultative anaerobe Shewanella oneidensis MR-1. Our experiments demonstrate that enzymatic activity is retained under the sample and protein separation methods described, as shown by positive malate dehydrogenase activity results. We have also found protein interactions within both the soluble and membrane fractions. The method described will be useful for the characterization of the functional proteomes of microbial systems.     

Residues in the first extracellular loop of a G protein-coupled receptor play a role in signal transduction

The Saccharomyces cerevisiae pheromone, alpha-factor (WHWLQLKPGQPMY), and Ste2p, its G protein-coupled receptor, were used as a model system to study ligand-receptor interaction. Cys-scanning mutagenesis on each residue of EL1, the first extracellular loop of Ste2p, was used to generate a library of 36 mutants with a single Cys residue substitution. Mutation of most residues of EL1 had only negligible effects on ligand affinity and biological activity of the mutant receptors. However, five mutants were identified that were either partially (L102C and T114C) or severely (N105C, S108C, and Y111C) compromised in signaling but retained binding affinities similar to those of wild-type receptor. Three-dimensional modeling, secondary structure predictions, and subsequent circular dichroism studies on a synthetic peptide with amino acid sequence corresponding to EL1 suggested the presence of a helix corresponding to EL1 residues 106 to 114 followed by two short beta-strands (residues 126 to 135). The distinctive periodicity of the five residues with a signal-deficient phenotype combined with biophysical studies suggested a functional involvement in receptor activation of a face on a 3(10) helix in this region of EL1. These studies indicate that EL1 plays an important role in the conformational switch that activates the Ste2p receptor to initiate the mating pheromone signal transduction pathway.     

Expression patterns of two new members of the Semaphorin family in Drosophila suggest early functions during embryogenesis

We report the sequence and expression analysis of two new Drosophila members of the Semaphorin family. Both proteins show the presence of Semaphorin domains and transmembrane domains. Both genes are expressed maternally and in embryos, and reveal distinct expression patterns much earlier than the onset of neurogenesis. We also present an overview of the domain structure of all so far known semaphorins in Drosophila. Furthermore, we compared all Drosophila and C. elegans Semaphorins and discuss them in the light of their evolution.