Enzymatic synthesis of novel fructosylated compounds by Ffase from Schwanniomyces occidentalis in green solvents

Glycerol, as a good acceptor for Ffase, produces novel fructosylated derivatives with biotechnological potential.

Complexes of Antimony(III)

Lewis acidity of antimony(III) halides and their organo substituted derivatives is well known. The molecules SbX3 are good acceptor and a wide range of neutral complexes have been prepared but it seems antimony trichloride is a weak acceptor as compared to antimony pentachloride. The halide complexes are more interesting because of the part played by the lone pair in determining the stereochemistry where 1:1 complexes have trigonal bipyramidal and 1:2 complexes have square pyramidal configurations. Complexes of antimony trichloride with aromatic hydrocarbon are also known but the presence of organic group in a molecule reduces its capacity to form complexes.DOI: http://dx.doi.org/10.3126/av.v4i0.12357Academic Voices Vol.4 2014: 45-48

3′-immature tRNATrp is required for ribosome inactivation by gelonin,a plant RNA N-glycosidase

Inactivation of ribosomes by gelonin, a ribosome-inactivating protein with RNA N-glycosidase activity on 28 S rRNA, requires macromolecular cofactors present in post-ribosomal supernatants. One of these cofactors has been purified from a rat liver extract and identified as an RNA about 70 nt long which in sequence analysis shows a high level of similarity with mammalian (bovine) tRNA(Trp). The pattern of the sequencing gel is consistent with the co-existence in the preparation of two 3′-immature tRNA(Trp) species, missing only A75, or both A75 and C74. In the presence of ATP, CTP and tRNA nucleotidyltransferase, the gelonin-stimulating RNA is a good acceptor of tryptophan. An oligodeoxynucleotide complementary to positions 55 to 72 of mammalian (bovine) tRNA(Trp) hybridizes with the gelonin-stimulating RNA as demonstrated by gel mobility shift and ribonuclease H digestion. The oligodeoxynucleotide-directed ribonuclease H treatment also abolishes the gelonin-promoting activity of crude preparations of RNA, giving strong evidence that the only active RNA is a tRNA(Trp)-like molecule.

Effects of Hyperthermal Carbon Subimplantation Doping on the Raman Spectra of Gaas

ABSTRACTThe structural effects of low-energy (30-500 eV), mass separated C12 Ion doping of GaAs simultaneous with conventional solid source MBE growth have been studied using room-temperature raman scattering, Hall-effect, transmission electron microscopy and 2K photoluminesence measurements for GaAs epitaxy temperatures of 550 ºC. Results indicate good acceptor activation without detectable residual damage is achieved for ion energies ≤ 240 eV, while at EIon = 500 eV, residual damage is present with a corresponding reduction in electrical activation. Low-energy TRIM calculations indicate that the damage is related to the increased depth distribution of vacancies and interstitials created during the higher (500 eV) implantation process which can not be annealed out at growth temperatures. Constant energy (100 eV) film growth experiments for a range of implantation currents (45 pA/cm2 - 45 nA/cm2) and growth temperatures of 550 and 550 ºC, show LO Raman peak broadening and mode hardening for currents ≥15 nA while maintaining very high C acceptor activation. This is interpreted as residual stress due to small amounts of interstitial C in the highest doped films. Both Hall mobility measurements and photoluminesence show no evidence of C dopant compensation.

Substrate specificity and distribution of UDP-GalNAc:sialylparagloboside N-acetylgalactosaminyltransferase in the human stomach

The detailed substrate specificity of the UDP-GalNAc:sialylparagloboside N-acetylgalactosaminyltransferase to form the Sd(a+) blood group active carbohydrate determinant GalNAc beta 1-4(NeuAc alpha 2-3)Gal was studied using a membrane fraction prepared from human gastric fundic mucosa. Various sialosylated oligosaccharides and gangliosides were examined as acceptor substrates. Oligosaccharide substrates were fluorescence-labelled with 2-aminopyridine, and the transferase activity was quantified by h.p.l.c. using a reversed-phase column. The structures of the products were determined by glycosidase degradation and proton n.m.r. 3′-Sialyl-lactose (II3NeuAcLac), 3′-sialyl-lactotetraose (IV3NeuAcLc4), and 3′-sialyl-lactoneotetraose (IV3NeuAcnLc4) were good substrates for the beta 1-4GalNAc transferase in gastric fundic mucosa, but 6′-sialyl-lactoneotetraose (IV6NeuAcnLc4) or 6′-sialyl-lactose (II6NeuAcLac) were not. Gangliosides with a terminal NeuAc alpha 2-3Gal residue such as GM3, sialylparagloboside, GM1b and GD1a were also studied. The activity of beta 1-4GalNAc transfer to sialylparagloboside was much higher than that to GM2, GM1b or GD1a in spite of them having the same terminal residue. Measurement of the activity of the beta 1-4GalNAc transferase in biopsy specimens demonstrated that the activity was localized in gastric fundic mucosa and was absent in pyloric mucosa, intestinal metaplasia and gastric cancer tissue. Thus the beta 1-4GalNAc transferase present specifically in fundic mucosa required a NeuAc alpha 2-3Gal residue connected to either type-1-chain or type-2-chain oligosaccharides. In glycolipids, the acceptor specificity was restricted to NeuAc alpha 2-3Gal beta 1-4GlcNAc because the NeuAc alpha 2-3Gal beta 1-3GalNAc structure in ganglio-series glycolipids was not a good acceptor substrate.

ON THE INTERMOLECULAR FORCE FIELD OF NITRILES

The nature of the intermolecular force field of the nitriles is considered on the basis of the electron orbital structure and charge distribution of the nitrile group. The directional nature of the force field is due to a well-directed lone pair orbital on the N atom, which may be expected to exhibit strong donor properties, and two π-orbitals which may exhibit weak donor properties. Accordingly with good acceptor molecules such as chloroform and hydrogen chloride, simple 1:1 molecular addition compounds should occur. The existence of molecular complexes of this type was confirmed with the aid of binary freezing-point diagrams which were determined for aceto-, propio-, butyro-, and benzo-nitrile with chloroform and hydrogen chloride. The 1:1 association complex was absent, however, in the system acetonitrile–chloroform. This is accounted for by the stronger association occurring in acetonitrile itself, the nature of which is discussed. The structure of the 1:1 molecular complexes is considered. Additional molecular complexes with lower nitrile mole ratios are indicated in the freezing-point diagrams. Of particular interest are the well-defined compounds appearing in the nitrile – hydrogen chloride systems with the composition RCN•5HCl. The possibility that the π-orbitals of the nitrile group may function as donors in these compounds is discussed, and a tentative structure is suggested.