A novel approach for the solid phase synthesis of DNA-peptide conjugates

The strategy of this study involves automated synthesis of oligonucleotides on a CPG support using standard cyanoethyl phosphoramidite chemistry followed by covalent linkage to peptide fragments bearing a free terminal alpha-amino group and residues with protected side chains. Conjugation was formed through an alkyldiisocyanate linker. Conjugates were isolated by cleavage from the solid support and deprotection in one step.     

A new method for the preparation of crystalline L-arabinose from arabinoxylan by enzymatic hydrolysis and selective fermentation with yeast

Arabinoxylan (`Cellace') corn fiber, containing 28.1% (w/w) as l-arabinose and 32.8% (w/w) as d-xylose, was hydrolyzed by a crude enzyme containing -xylanase, -xylosidase and -l-arabinofuranosidase originating from the extracellular culture broth of Penicillium funiculosum. The resultant hydrolysate contained l-arabinose, d-xylose and small amounts of other mono- and oligosaccharides. The l-arabinose and d-xylose were 21.3% (w/w) and 18.7% (w/w), respectively, based on the initial arabinoxylan. Williopsis saturnus var. saturnus, which metabolizes d-xylose without using l-arabinose, was aerobically cultured in the hydrolysate at 30 °C for 96 h. The sugar solution after removal of yeast cells contained l-arabinose and d-xylose which were 20.3% (w/w) and 0.002% (w/w), respectively, of the initial arabinoxylan. The solution was decolorized with activated carbon, and deionized with cation- and anion-exchange resins. The clear sugar solution thus obtained was composed of l-arabinose and d-xylose which were 19.3% (w/w) and 0.001% (w/w), respectively, of the initial arabinoxylan. After concentration of the sugar solution under reduced pressure, followed by crystallization of l-arabinose, 16% (w/w) l-arabinose (based on the initial arabinoxylan) was obtained as crude crystals. No d-xylose was detected in the final preparation.     

Glycosphingolipid deficiency affects functional microdomain formation in Lewis lung carcinoma cells

In view of the increasing evidence that gangliosides in membrane microdomains or rafts are closely associated with various signal transducing molecules including Src family kinases, we compared rafts in two subclones of 3LL mouse lung carcinoma cell line, J18 and J5, characterized by high and very low GM3 ganglioside contents, respectively. Rafts were isolated from cell lysates as low density detergent-insoluble microdomains (DIM) by sucrose density gradient centrifugation. J5 and J18 cells expressed comparable amounts of Src family kinases and the majority of Src kinases in both clones were concentrated in their DIMs, suggesting that GM3 is not necessary for DIM localization of Src kinases and there is no direct interaction between Src and GM3. However, the Src kinases were eliminated from DIMs after depletion of the major neutral GSLs of J5 cells, glucosylceramide and lactosylceramide, by an inhibitor of glucosylceramide synthase (D-PDMP), indicating that GSLs in general are required for Src kinase association to DIM. J5 and the D-PDMP-treated J5 cells had very similar DIM protein profiles and moreover cholesterol and sphingomyelin in the GSL-depleted cells were enriched in DIM similar to the untreated control cells. Interestingly, the levels of tyrosine-phosphorylated DIM proteins and cell proliferation of J5 cells were much lower than those of J18 cells, suggesting that GM3 might be involved in tyrosine phosphorylation of DIM proteins required for cell growth. Thus, our data suggest that GSLs are essential for functional raft formation.     

The 70-kDa peroxisomal membrane protein (PMP70) an ATP-binding cassette transporter

The 70-kDa peroxisomal membrane protein (PMP70) is one of major components of peroxisomal membranes. In rodents, PMP70 is markedly induced by administration of hypolipidemic agents in parallel with peroxisome proliferation and the induction of peroxisomal fatty acid β-oxidation enzymes. PMP70 is an ATP-binding cassette transporter, identified for the first time in intracellular membranes of eukaryotic cells. The authors' recent studies suggest that PMP70 is synthesized on free polysomes and posttranslationally inserted into peroxisomal membranes, and assembles as dimeric or oligomeric forms on peroxisomal membranes. PMP70 is suggested to be involved in metabolic transport of long-chain acyl-CoA across peroxisomal membranes.     

Ceramide dihexosides from the spermatozoa of the starfish, Asterias amurensis, consist of gentiobiosyl- cellobiosyl-, and lactosylceramide

Ceramide dihexoside was obtained from the spermatozoa of the starfish, Asterias amurensis. Gas-liquid chromatography of the methanolysate to determine the sugar composition of the lipid demonstrated an unequal ratio of glucose and galactose, implying that two or more glycolipids are present. They were separated by thin-layer chromatography on a borate-impregnated plate into two bands. From the results of methylation analysis and chromic acid oxidation, one was determined to be lactosylceramide, while the other was suggested to be a mixture of two diglucosylceramides: gentiobiosylceramide (Glc beta 1-6Glc beta 1-1Cer) and cellobiosylceramide (Glc beta 1-4Glc beta 1-1Cer). The molar ratio of gentiobiosyl-, cellobiosyl-, and lactosylceramide was estimated to be 0.7 : 0.3 : 1.0. Ceramide dihexosides obtained from another batch of the spermatozoa, collected at the same place in a different year, consisted almost exclusively of gentiobiosylceramide as confirmed by proton-nuclear magnetic resonance spectroscopy and fast-atom bombardment mass-spectrometry. The fatty acid compositions of these glycolipids were similar and the main acids were 14h:0, 15h:0, 16h:0, 18h:0, and 24h:1 (constituting more than 80% of the total acids). The long-chain base compositions were qualitatively similar and the major constituents were commonly d18:2, d18:3, d19:3, d22:2, and t22:1. Lactosylceramide was rich in t22:1, while diglucosylceramides were rich in d22:2.     

A novel difucosylated neutral glycosphingolipid from the eggs of the sea urchin, Hemicentrotus pulcherrimus: II. Structural determination by two-dimensional NMR.

A novel fucosylglycolipid from the eggs of the sea urchin, Hemicentrotus pulcherrimus, was determined by using two-dimensional NMR methods. Subspectra extraction by the homonuclear Hartmann-Hahn method was useful for identification of the individual sugar components. The homonuclear Hartmann-Hahn and double-quantum-filtered correlated spectra were analyzed to establish the assignments of sugar proton resonances. On the basis of the resonance assignments, the linkages of the individual sugar components were determined to be as follows. [formula: see text] This glycolipid contains a novel skeletal structure with the linkages of GalNAc beta 1-4GlcNAc beta 1-4Glc beta. We also observed that 2-hydroxylation of the fatty acids induced appreciable chemical shift changes of the proton resonances of the phytosphingosine moiety as well as the anomeric proton resonance of the reducing terminal glucose.     

Isolation and molecular size of Clostridium botulinum type C toxin.

A procedure is described for the purification of hemagglutinin-free Clostridium botulinum type C toxin. The toxin was purified approximately 1,000-fold from the original culture supernatant in an overall yield of 60% to a final specific toxicity of 4.4 x 10(7) minimal lethal doses/mg of protein. The toxin had a molecular weight of 141,000 and consisted of a heavy and a light chain. The molecular weights of the subunits were approximately 98,000 and 53,000. When comparing the molecular size and composition of type C toxin to that of botulinum toxins of different types, some common features may be suggested; i.e., the toxin has a molecular weight between 141,000 to 160,000 and is comprised of a heavy and a light chain linked by disulfide bonds (or bond).