Concomitant increase in putrescine incorporation with transferrin uptake into rat reticulocytes.

Concomitant increase in putrescine incorporation with transferrin uptake into rat reticulocytes was found. [14C]Putrescine incorporation occurred in the presence of transferrin at 37 degrees C. The subcellular distribution of incorporated [14C]putrescine showed that the incorporation in the plasma membrane time dependently increased. Both 125I-labeled transferrin uptake and [14C]putrescine incorporation decreased when ethylene glycol bis(2-aminoethyl ether)-N,N,N',N'-tetraacetic acid was added, while it increased with the addition of A23187.     

Preferential CO oxidation promoted by the presence of H2 over K-Pt/Al2O3

In preferential CO oxidation in H2-rich gas, K-Pt/Al2O3(K/Pt = 10) was very effective in decreasing CO concentration below 10 ppm in the 375-410 K range, and the turnover frequency of the K-Pt/Al2O3 was 20 times as high as that of Pt/Al2O3 at 353 K; furthermore, the activity of CO oxidation was promoted drastically by the presence of H2.     

Novel carbohydrate-appended metal complexes for potential use in molecular imaging

Seven discrete sugar-pendant diamines were complexed to the {M(CO)(3)}(+) ((99m)Tc/Re) core: 1,3-diamino-2-propyl beta-D-glucopyranoside (L(1)), 1,3-diamino-2-propyl beta-D-xylopyranoside (L(2)), 1,3-diamino-2-propyl alpha-D-mannopyranoside (L(3)), 1,3-diamino-2-propyl alpha-D-galactopyranoside (L(4)), 1,3-diamino-2-propyl beta-D-galactopyranoside (L(5)), 1,3-diamino-2-propyl beta-(alpha-D-glucopyranosyl-(1,4)-D-glucopyranoside) (L(6)), and bis(aminomethyl)bis[(beta-D-glucopyranosyloxy)methyl]methane (L(7)). The Re complexes [Re(L(1)-L(7))(Br)(CO)(3)] were characterized by (1)H and (13)C 1D/2D NMR spectroscopy which confirmed the pendant nature of the carbohydrate moieties in solution. Additional characterization was provided by IR spectroscopy, elemental analysis, and mass spectrometry. Two analogues, [Re(L(2))(CO)(3)Br] and [Re(L(3))(CO)(3)Br], were characterized in the solid state by X-ray crystallography and represent the first reported structures of Re organometallic carbohydrate compounds. Conductivity measurements in H(2)O established that the complexes exist as [Re(L(1)-L(7))(H(2)O)(CO)(3)]Br in aqueous conditions. Radiolabelling of L(1)-L(7) with [(99m)Tc(H(2)O)(3)(CO)(3)](+) afforded in high yield compounds of identical character to the Re analogues. The radiolabelled compounds were determined to exhibit high in vitro stability towards ligand exchange in the presence of an excess of either cysteine or histidine over a 24 h period.     

Novel synthesis of carbapenam by intramolecular attack of lactam nitrogen toward eta1-allenyl and eta3-propargylpalladium complex

When a THF solution of beta-lactam having propargyl phosphate was warmed in the presence of 5 mol % of Pd(2)(dba)(3) x CHCl(3), 20 mol % of a bidentate ligand, and sodium acetate (1.5 equiv) at 40 degrees C for 22 h, carbapenam was produced in high yield. In this reaction, the lactam nitrogen attacked the central carbon of a eta(3)-propargylpalladium complex, which was formed from propargyl phosphate and Pd(0).     

Presence of peroxyradicals in cigarette smoke and the scavenging effect of shikonin, a naphthoquinone pigment

Using a new method having been developed for the purpose of quantitative determination for peroxyradicals, the presence of peroxyradicals was proved in cigarette smoke. In brief, peroxyradicals in cigarette smoke were measured by ESR spectrometry coupled to non-reductive scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH). As a result, peroxyradicals were found to be major reactive oxygen species (ROS) since the concentration of peroxyradicals recovered from cigarette smoke was much higher than that of any of other ROS (superoxide and hydroxyl radical) and nitric oxide. Furthermore, several antioxidants (ascorbic acid, reduced glutathione, epigallocatechin gallate, shikonin) were examined for scavenging activity against peroxyradicals in the cigarette smoke. Among them shikonin alone exerted the scavenging activity, suggesting that shikonin is promising antioxidant for cigarette filters because of its effectiveness against broad range of ROS including peroxyradicals, heat resistance, nonvolatility and high affinity to the filter.     

From penicillin to penem and carbapenem. VI1) : Synthesis of dethiathienamycin

A new C₃-unit substitution reaction at C-4 position of 4- acetoxyazetidinone derivative ($\text{1}$ and $\text{5}$) by tetraallyltin ($\text{2}$) in the presence of 1/10 eq. of BF₃-ether in methylene chloride is described. From 4-allylazetidinone derivative ($\text{3}$) via ylid intermediate ($\text{14}$) dethiathienamycin ($\text{16}$) was synthesized.     

Completely stereocontrolled synthesis of the right fragment of salinomycin,a polyether antibiotic,by means of the chelation-controlled grignard reaction

In the course of our synthetic study of salinomycin ($\text{1}$), an ionophorous polyether antibiotic, the γ-lactone ($\text{2}$) corresponding to the C-21～C-30 fragment (the right fragment) of $\text{1}$ was synthesized from D-mannitol and ethyl L-lactate as chiral starting materials. The complete stereocontrol for the construction of new chiral centers has been achieved by means of the chelation-controlled Grignard reaction and the tetrahydropyran synthesis via the acid catalyzed epoxide ring opening.     

Influence of amino acid side chain packing on Fe-methionine coordination in thermostable cytochrome C

Paramagnetic NMR and optical studies of the oxidized forms of mesophile Pseudomonas aeruginosa cytochrome c(551) and its quintuple mutant (F7A/V13M/F34Y/E43Y/V78I), and thermophile Hydrogenobacter thermophilus cytochrome c(552) demonstrated that the amino acid side chain packings in the protein interior influence the coordination bond between the heme iron and the axial methionine in the proteins. The strength of heme axial coordinations was found to correlate with the overall protein thermostability.     

Interaction between amphiphiles and water molecules in concentrated bilayer aqueous colloids

Interaction between amphiphiles and water molecules in micelle or bilayer structure has been investigated using aqueous colloids of various amphiphiles through the rheological data and the spin-lattice relaxation timeT ₁ of the proton of water molecule.T ₁ of the water proton has been measured by the inversion recovery method and determined as a single exponential relaxation process.The chemical shift of the water proton is almost independent of the amphiphilic concentration; however, it shifts toward a higher magnetic field with increasing temperature in a way similar to that in pure water and in the amphiphilic aqueous systems. These facts mean that there is no significant difference in the magnetic field environment of the water protons in these systems.The water molecule is not necessarily bound in the fully developed micelle or bilayer (rod-like or lamella) structure which induces the high viscosity or high rigidity of the colloidal system. On the other hand, the water molecule is bound in the micelle colloids of amphoteric amphiphiles or amphiphiles whose molecular assembly creates a relatively strong electrostatic field. The activation entropy of the bound water is negative and this suggests that water molecules assume some ordered structure in the bound state.     

Nature of the active component in the catalytic system prepared from titanium(III) chloride(AA), ethylaluminum dichloride,and tetrakis(dimethylamino)silane,in the polymerization of propylene

The chemistry of the titanium(III) chloride(AA)–ethylaluminum dichloride–tetrakis-(dimethylamino)silane system for the polymerization of propylene was studied. A complex of ethylaluminum dichloride with tetrakis(dimethylamino)silane was isolated. It was shown that this complex contains ethylaluminum dichloride and tetrakis(dimethylamino)silane in the ratio of 2:1. This complex with titanium(III) chloride is responsible for the polymerization activity.