A theoretical and comparative CNDO study of chlorophylls a and b and their beryllium homologs

CNDO/II calculations of chlorophylls a and b and their beryllium homologs show that the 3d atomic orbitals of the metal atoms contribute significantly to the σ and π bonding energies. In both chlorophylls a and b replacement of magnesium by beryllium stabilizes the total molecular energy by 40 kcal/mol.     

The Tetraspanins CD9 and CD81 Regulate CD9P1-Induced Effects on Cell Migration

CD9P-1 is a cell surface protein with immunoglobulin domains and an unknown function that specifically associates with tetraspanins CD9 and CD81. Overexpression of CD9P-1 in HEK-293 cells induces dramatic changes in cell spreading and migration on various matrices. Experiments using time-lapse videomicroscopy revealed that CD9P-1 expression has led to higher cell motility on collagen I but lower motility on fibronectin through a β1-integrins dependent mechanism. On collagen I, the increase in cell motility induced by CD9P-1 expression was found to involve integrin α2β1 and CD9P-1 was observed to associate with this collagen receptor. The generation of CD9P-1 mutants demonstrated that the transmembrane and the cytoplasmic domains are necessary for inducing effects on cell motility. On the other hand, expression of tetraspanins CD9 or CD81 was shown to reverse the effects of CD9P-1 on cell motility on collagen I or fibronectin with a concomitant association with CD9P-1. Thus, the ratio of expression levels between CD9P-1 and its tetraspanin partners can regulate cell motility.     

An experimental and theoretical approach to the molecular structure of 2-{4-[3-(2,5-dimethylphenyl)-3-methylcyclobutyl]thiazol-2-yl}isoindoline-1,3-dione

The title compound, 2-{4-[3-(2,5-dimethylphenyl)-3-methylcyclobutyl]thiazol-2-yl}isoindoline-1,3-dione (C₂₄H₂₂N₂O₂S), was synthesized and characterized by IR-NMR spectroscopy and single-crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P2₁/c with a?=?19.7799(13) Å, b?=?6.7473(4) Å, c?=?15.7259(9) Å and β?=?103.416(5)°. In addition, the molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) ¹H and ¹³C chemical shift values of the title compound in the ground state have been calculated by using the Hartree-Fock (HF) and density functional method (DFT/B3LYP) with 6–31G(d), 6–31 + G(d,p) and LANL2DZ basis sets, and compared with the experimental data. To determine conformational flexibility, molecular energy profile of the title compound was obtained by semi-empirical (AM1) calculations with respect to two selected degrees of torsional freedom, which were varied from ?180° to +180° in steps of 5°. Besides, molecular electrostatic potential, frontier molecular orbitals (FMO) analysis and thermodynamic properties of the title compound were investigated by theoretical calculations.     

Multiple molecular forms of rat superior cervical ganglion acetylcholinesterase: Developmental aspects in primary cell culture and during postnatal maturation in vivo

Four main molecular forms of acetylcholinesterase (AChE) can be solubilized from newborn rat superior cervical ganglia (SCG), homogenized in the presence of a high-ionic-strength, detergent-containing medium. These forms, respectively referred to as 16, 10, 6.5, and 4 S, are characterized by their sedimentation coefficients. Their relative proportions in SCG are notably different in vivo during postnatal maturation, and in culture. The 16-S AChE appears to be mainly neuronal in origin, is maintained in culture independently of original presynaptic in vivo elements, and its cellular pool is not depleted in the presence of tetrodotoxin (TTX).     

On the biosynthesis of biotin in Achromobacter IVSW a reinvestigation

[3-¹⁴C, ³⁵S]-L-cysteine was tested as precursor of biotin in Achromobacter IVSW. No significant incorporation was observed, in contradiction with the data previously reported. On the other hand, Achromobacter IVSW converts [³H, ¹⁴C]-dethiobiotin into biotin. This suggests that biotin is biosynthesized in Achromobacter according to the classical dethiobiotin pathway.     

Differential apoptotic pathways activated in response to Cu-induced or HOCl-induced LDL oxidation in U937 monocytic cell line

We compared the apoptotic mechanism involved in U937 human monocytic cell line in presence of oxidized low-density lipoproteins (oxLDL) obtained after treatment with hypochlorous acid (HOCl) or copper (Cu).Both types of oxLDL induced U937 apoptotic cell death via the mitochondrial pathway. In contrast to HOCl-oxLDL, Cu-oxLDL induced apoptosis via a caspase-independent mechanism, with no activation of pro-caspase-3, but via the release of apoptosis inducing factor (AIF) from mitochondria.The apoptotic program of the monocyte differs depending on the mode of LDL oxidation, based on differences in the oxidatively modified components of the two oxLDL types.     

Essai chimiosystématique sur la tribu des Lotées

A survey of the leaves and flowers of 62 representatives of the tribe Loteae (Leguminosae) showed the presence of several classes of flavonoids: flavonol 7-methyl ethers (rhamnocitrin, rhamnetin), 8-O-substituted flavonols (gossypetin, limocitrin, sexangularetin, corniculatusin), 3′,4′,5′-tri-O-substituted flavonols (myricetin, mearnsetin, syringetin, laricitrin), proanthocyanidins and flavone-C-glycosides. The trisubstitution of the B-ring and the 8-O-substitution of the A-ring allow the definition of a major group including the genera Dorycnium, Bonjeania, Lotus and Tetragonolobus. The presence of proanthocyanidins and 7-O-methylation determine a second group consisting of the genus Anthyllis. Finally, Securigera, on the basis of its flavonoid chemistry, appears to be rather remote from other members of the tribe.