Metal binding to pyridoxal derivatives. An NMR study of the interaction of Eu(III) with pyridoxal phosphate and pyridoxamine phosphate

The solution conformations of pyridoxal-5′-phosphate and pyridoxamine-5′-phosphate have been investigated using Eu(III) as a nuclear magnetic resonance shift probe. Binding of Eu(III) to pyridoxal phosphate results in the formation of two complexes, at the phosphate group and theo-hydroxy-aldehyde moiety, which are in slow exchange on the nuclear magnetic resonance time-scale. The lanthanide-induced pseudo contact shifts calculated using the McConnell-Robertson equation (J. Chem. Soc. (1950), 22, 1561) are in good agreement with the experimentally observed values for both pyridoxal phosphate and pyridoxamine phosphate and lead to a family of closely related conformations

The crystal structure of benzyloxycarbonyl-(α-aminoisobutyryl)-L-alanyl methyl ester

Crystals of the title compound, C20,H29,N3,O6, are monoclinic, space group P2, with a = 8-839 (3), b = f10.818 (3), c = 11.414 (2) A, β = 95.69 (2)° Z = 2; final R = 0.053. The molecular conformation is defined by the following angles (φ, ψ): Aib-1 58- 1, 36.8; Aib-2 68.3, 18.6; Ala-3 (φ) -136.2°. The molecule adopts a type 111 β -turn conformation stabilized by an intramolecular hydrogen bond between the CO of the benzyloxycarbonyl group and the NH of the alanyl residue. The hydrogen-bond parameters are N···O 2-904 Å and ∠NH···O 156.9°

Synthesis of agarose-metal/semiconductor nanoparticles having superior bacteriocidal activity and their simple conversion to metal-carbon composites

Agarose, a naturally occurring biopolymer is used for the stabilization of metal, semiconductor nanoparticles. Ag and Cu nanoparticles stabilized in agarose matrix show excellent antibacterial activity against E. coli bacteria. The well dispersed metal nanoparticles within the agarose composite films can be readily converted to carbon-metal composites of catalytic importance

Effect of amino acid substitutions at the subunit interface on the stability and aggregation properties of a dimeric protein: role of Arg 178 and Arg 218 at the dimer interface of thymidylate synthase

The significance of two interface arginine residues on the structural integrity of an obligatory dimeric enzyme thymidylate synthase (TS) from Lactobacillus casei was investigated by thermal and chemical denaturation. While the R178F mutant showed apparent stability to thermal denaturation by its decreased tendency to aggregate, the Tm of the R218K mutant was lowered by 5°C. Equilibrium denaturation studies in guanidinium chloride (GdmCl) and urea indicate that in both the mutants, replacement of Arg residues results in more labile quaternary and tertiary interactions. Circular dichroism studies in aqueous buffer suggest that the protein interior in R218K may be less well-packed as compared to the wild type protein. The results emphasize that quaternary interactions may influence the stability of the tertiary fold of TS. The amino acid replacements also lead to notable alteration in the ability of the unfolding intermediate of TS to aggregate. The aggregated state of partially unfolded intermediate in the R178F mutant is stable over a narrower range of denaturant concentrations. In contrast, there is an exaggerated tendency on the part of R218K to aggregate in intermediate concentrations of the denaturant. The 3 Å crystal structure of the R178F mutant reveals no major structural change as a consequence of amino acid substitution. The results may be rationalized in terms of mutational effects on both the folded and unfolded state of the protein. Site specific amino acid substitutions are useful in identifying specific regions of TS involved in association of non-native protein structures

Molecular structure of Boc-Aib-Aib-Phe-Met-NH<SUB>2</SUB>·DMSO. A fragment of a biologically active enkephalin analogue

The tetrapeptide t-butyloxycarbonyl-&#945;-aminoisobutyryl-&#945;-aminoisobutyryl-L- phenylalanyl-L-methionyl amide crystallizes in the orthorhombic space group P212121 with a= 9.096, b= 18.067, c= 21.701 &#197; and Z= 4. The crystals contain one molecule of dimethyl sulphoxide (DMSO) associated with each peptide. The structure has been solved by direct methods and refined to an R value of 0.103 for 2 672 observed reflections. The peptide adopts a distorted 310 helical structure stabilized by two intramolecular 4 &#8594; 1 hydrogen bonds between the Boc CO and Aib(1) CO groups and the NH groups of Phe(3) and Met(4), respectively. A long hydrogen bond (N...O = 3.35 &#197;) is also observed between Aib(2) CO and one of the terminal amide hydrogens. The DMSO molecule is strongly hydrogen bonded to the Aib(1) NH group. The solid-state conformation agrees well with proposals made on the basis of n.m.r. studies in solution

Mars Science Helicopter Conceptual Design

Robotic planetary aerial vehicles increase the range of terrain that can be examined, compared to traditional landers and rovers, and have more near-surface capability than orbiters. Aerial mobility is a promising possibility for planetary exploration as it reduces the challenges that difficult obstacles pose to ground vehicles. The first use of a rotorcraft for a planetary mission will be in 2021, when the Mars Helicopter technology demonstrator will be deployed from the Mars 2020 rover. The Jet Propulsion Laboratory and NASA Ames Research Center are exploring possibilities for a Mars Science Helicopter, a second-generation Mars rotorcraft with the capability of conducting science investigations independently of a lander or rover (although this type of vehicle could also be used assist rovers or landers in future missions). This report describes the conceptual design of Mars Science Helicopters. The design process began with coaxial-helicopter and hexacopter configurations, with a payload in the range of two to three kilograms and an overall vehicle mass of approximately twenty kilograms. Initial estimates of weight and performance were based on the capabilities of the Mars Helicopter. Rotorcraft designs for Mars are constrained by the dimensions of the aeroshell for the trip to the planet, requiring attention to the aircraft packaging in order to maximize the rotor dimensions and hence overall performance potential. Aerodynamic performance optimization was conducted, particularly through airfoils designed specifically for the low Reynolds number and high Mach number inherent in operation on Mars. The final designs show a substantial capability for science operations on Mars: a 31 kg hexacopter that fits within a 2.5 m diameter aeroshell could carry a 5 kg payload for 10 min of hover time or over a range of 5 km

PBEF1/NAmPRTase/Visfatin: a potential malignant astrocytoma/glioblastoma serum marker with prognostic value

Malignant astrocytomas comprise anaplastic astrocytoma (AA; grade III) and Glioblastoma (GBM; grade IV). GBM is the most malignant with a median survival of 10-12 months in patients. Using cDNA microarray based expression profiling of different grades of astrocytomas, we identified several fold increased levels of PBEF1 transcripts in GBM samples. Pre-B-cell colony enhancing factor 1 gene (PBEF1) encodes Nicotinamide phosphoribosyltransferase (NAmPRTase), which catalyses the rate limiting step in the salvage pathway of NAD metabolism in mammalian cells. Further validation using real time RT-qPCR on an independent set of tumor samples (n=91) and normal brain samples (n=9), GBM specific higher expression of PBEF1 was confirmed. Immunohistochemical staining for PBEF1 on a subset of the above samples largely reinforced our finding. We carried out ELISA analysis on serum samples of astrocytoma patients to determine whether this protein levels would correlate with the presence of tumor and tumor grade. PBEF1 serum levels were substantially elevated in many of the AA and GBM patients. Statistical analysis of these data indicates that in patients with astrocytoma, serum PBEF1 levels correlate with tumor grade and is highest in GBM. Immunohistochemical analysis of an independent set of 51 retrospective GBM cases with known survival data revealed that PBEF1 expression in the tumor tissue along with its co-expression with p53 was associated with poor survival. Thus, we have identified PBEF1 as a potential malignant astrocytoma serum marker and prognostic indicator among GBMs

Pharmacological modulation of Kv3.1 mitigates auditory midbrain temporal processing deficits following auditory nerve damage

Higher stages of central auditory processing compensate for a loss of cochlear nerve synapses by increasing the gain on remaining afferent inputs, thereby restoring firing rate codes for rudimentary sound features. The benefits of this compensatory plasticity are limited, as the recovery of precise temporal coding is comparatively modest. We reasoned that persistent temporal coding deficits could be ameliorated through modulation of voltage-gated potassium (Kv) channels that regulate temporal firing patterns. Here, we characterize AUT00063, a pharmacological compound that modulates Kv3.1, a high-threshold channel expressed in fast-spiking neurons throughout the central auditory pathway. Patch clamp recordings from auditory brainstem neurons and in silico modeling revealed that application of AUT00063 reduced action potential timing variability and improved temporal coding precision. Systemic injections of AUT00063 in vivo improved auditory synchronization and supported more accurate decoding of temporal sound features in the inferior colliculus and auditory cortex in adult mice with a near-complete loss of auditory nerve afferent synapses in the contralateral ear. These findings suggest modulating Kv3.1 in central neurons could be a promising therapeutic approach to mitigate temporal processing deficits that commonly accompany aging, tinnitus, ototoxic drug exposure or noise damage

Novel glioblastoma markers with diagnostic and prognostic value identified through transcriptome analysis

Purpose: Current methods of classification of astrocytoma based on histopathologic methods are often subjective and less accurate. Although patients with glioblastoma have grave prognosis, significant variability in patient outcome is observed. Therefore, the aim of this study was to identify glioblastoma diagnostic and prognostic markers through microarray analysis. Experimental Design: We carried out transcriptome analysis of 25 diffusely infiltrating astrocytoma samples [WHO grade II - diffuse astrocytoma, grade III - anaplastic astrocytoma, and grade IV - glioblastoma (GBM)] using cDNA microarrays containing 18,981 genes. Several of the markers identified were also validated by real-time reverse transcription quantitative PCR and immunohistochemical analysis on an independent set of tumor samples (n = 100). Survival analysis was carried out for two markers on another independent set of retrospective cases (n = 51). Results: We identified several differentially regulated grade-specific genes. Independent validation by real-time reverse transcription quantitative PCR analysis found growth arrest and DNA-damage-inducible α (GADD45α) and follistatin-like 1 (FSTL1) to be up-regulated in most GBMs (both primary and secondary), whereas superoxide dismutase 2 and adipocyte enhancer binding protein 1 were up-regulated in the majority of primary GBM. Further, identification of the grade-specific expression of GADD45α and FSTL1 by immunohistochemical staining reinforced our findings. Analysis of retrospective GBM cases with known survival data revealed that cytoplasmic overexpression of GADD45α conferred better survival while the coexpression of FSTL1 with p53 was associated with poor survival. Conclusions: Our study reveals that GADD45α and FSTLI are GBM-specific whereas superoxide dismutase 2 and adipocyte enhancer binding protein 1 are primary GBM-specific diagnostic markers. Whereas GADD45α overexpression confers a favorable prognosis, FSTL1 overexpression is a hallmark of poor prognosis in GBM patients