Tucumanin, a β-hydroxy-γ-lactone bistetrahydrofuranic acetogenin from Annona cherimolia, is a potent inhibitor of mitochondrial complex I

A new β-hydroxy-γ-methyl-γ-lactone bistetrahydrofuranic acetogenin, tucumanin, with the infrequent symmetrical threo/trans/threo/trans/ threo relative configuration at the tetrahydrofuran rings was isolated from Annona cherimolia (Annonaceae) seeds. The inhibitory potency on the mitochondrial complex I of acetogenins with this relative configuration (tucumanin and asimicin) was compared with that shown by the corresponding pairs with an asymmetrical threo/trans/threo/trans/erythro relative configuration (laherradurin/rolliniastatin-2, and itrabin/molvizarin). All these compounds act as selective inhibitors of mitochondrial complex 1 in the 0.18 - 1.55 nM range.Fil: Barrachina, Isabel. Universidad de Valencia; EspañaFil: Neske, Adriana. Universidad Nacional de Tucumán; ArgentinaFil: Granell, Susana. Universidad de Valencia; EspañaFil: Bermejo, Almudena. Universidad de Valencia; EspañaFil: Chahboune, Nadia. Universidad de Valencia; EspañaFil: El Aouad, Noureddine. Universidad de Valencia; EspañaFil: Alvarez, Olga. Universidad Nacional de Tucumán; ArgentinaFil: Bardon, Alicia del Valle. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina. Universidad Nacional de Tucumán; ArgentinaFil: Zafra Polo, M. Carmen. Universidad de Valencia; Españ

Glycyl-L-proline hemihydrate at 298 K

The crystal structure of glycyl-L-proline (GLY-PRO) hemihydrate, C(7)H(12)N(2)O(3)(.)0.5H(2)O, has two molecules of GLY-PRO in the asymmetric unit; one molecule adopts the cis configuration at the peptide bond and the other adopts the trans configuration.</p

Chemotaxis of Bracken Spermatozoids : The Role of Bimalate Ions

1. Bracken spermatozoids are chemotactically attracted by malic acid salts and in a pH gradient aggregate between pH 3.5 and 5.6. 2. This response to pH occurs only when the sperm suspension contains malate. 3. At higher pH's, the response to an H+ gradient is as strong as the response to a malate gradient. 4. These observations suggest that bracken spermatozoids are sensitive to the bimalate ion rather than the malate ion. This is consistent with an earlier suggestion that chemotactic activity is associated with the cis-configuration, for the bimalate ion will have this configuration, while the malate ion and the malic acid molecule will have the trans-configuration

Optical Resolution and Configuration of Trans-2,3-epoxybutyric Acid

Optical resolution of epoxy derivative of butyric acid with brucine and configuration determination by treatment with ammoni

A stable static Universe?

Starting from the assumption that general relativity might be an emergent phenomenon showing up at low-energies from an underlying microscopic structure, we re-analyze the stability of a static closed Universe filled with radiation. In this scenario, it is sensible to consider the effective general-relativistic configuration as in a thermal contact with an "environment" (the role of environment can be played, for example, by the higher-dimensional bulk or by the trans-Planckian degrees of freedom). We calculate the free energy at a fixed temperature of this radiation-filled static configuration. Then, by looking at the free energy we show that the static Einstein configuration is stable under the stated condition.Comment: 6 pages, no figures; uses revtex4; version accepted for publication; some phrasing changed; wrong coefficient correcte

Preliminary design characteristics of a subsonic business jet concept employing laminar flow control

Aircraft configurations were developed with laminar flow control (LFC) and without LFC. The LFC configuration had approximately eleven percent less parasite drag and a seven percent increase in the maximum lift-to drag ratio. Although these aerodynamic advantages were partially offset by the additional weight of the LFC system, the LFC aircraft burned from six to eight percent less fuel for comparable missions. For the trans-atlantic design mission with the gross weight fixed, the LFC configuration would carry a greater payload for ten percent fuel per passenger mile

Addendum to "Local Controllability of the Two-Link Magneto-Elastic Micro-Swimmer"

In the above mentioned note (, , published in IEEE Trans. Autom. Cont., 2017), the first and fourth authors proved a local controllability result around the straight configuration for a class of magneto-elastic micro-swimmers.That result is weaker than the usual small-time local controllability (STLC), and the authors left the STLC question open. The present addendum closes it by showing that these systems cannot be STLC

Functional Stoichiometry at the Nicotinic Receptor. The Photon Cross Section for Phase 1 Corresponds to Two Bis-Q Molecules per Channel

These experiments examine changes in the agonist-induced conductance that occur when the agonist-receptor complex is perturbed. Voltage-clamped Electrophorus electroplaques are exposed to the photoisomerizable agonist trans-Bis-Q A 1-µs laser flash photoisomerizes some trans-Bis-Q molecules bound to receptors; because the cis configuration is not an agonist, receptor channels close within a few hundred microseconds. This effect is called phase 1. We compare (a) the fraction of channels that close during phase 1 with (b) the fraction of trans-Bis-Q molecules that undergo trans → cis photoisomerization. Parameter a is measured as the fractional diminution in voltage-clamp currents during phase 1. Parameter b is measured by changes in the optical spectra of Bis-Q solutions caused by flashes . At low flash intensities, a is twice b, which shows that the channel can be closed by photoisomerizing either of two bound agonist molecules. Conventional dose-response studies with trans-Bis-Q also give a Hill coefficient of two. As a partial control for changes in the photochemistry caused by binding of Bis-Q to receptors, spectral measurements are performed on the photoisomerizable agonist QBr, covalently bound to solubilized acetylcholine receptors from Torpedo. The bound and free agonist molecules have the same photoisomerization properties. These results verify the concept that the open state of the acetylcholine receptor channel is much more likely to be associated with the presence of two bound agonist molecules than with a single such molecule

Color Detection Using Chromophore-Nanotube Hybrid Devices

We present a nanoscale color detector based on a single-walled carbon nanotube functionalized with azobenzene chromophores, where the chromophores serve as photoabsorbers and the nanotube as the electronic read-out. By synthesizing chromophores with specific absorption windows in the visible spectrum and anchoring them to the nanotube surface, we demonstrate the controlled detection of visible light of low intensity in narrow ranges of wavelengths. Our measurements suggest that upon photoabsorption, the chromophores isomerize from the ground state trans configuration to the excited state cis configuration, accompanied by a large change in dipole moment, changing the electrostatic environment of the nanotube. All-electron ab initio calculations are used to study the chromophore-nanotube hybrids, and show that the chromophores bind strongly to the nanotubes without disturbing the electronic structure of either species. Calculated values of the dipole moments support the notion of dipole changes as the optical detection mechanism.Comment: Accepted by Nano Letter