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Modulation of the biological function of a synthetic carbohydrate antigen related to Streptococcus pneumoniae infections
No full textThe role of C-15 in the biosynthesis of digitoxigenin
No full textThe 15-position of pregnane-type precursors is not involved in the 14β-hydroxylation process during the biosynthesis of digitoxigenin
The structure of syriogenin
No full textSyriogenin was demonstrated by chemical and spectroscopic evidence to have the structure 12β-hydroxyuzarigenin and confirmed by transformation into 3,12-diketo-5α,14α-etianic acid methyl ester
Synthesis of photoactivable probes for the study of glycosphingolipid-protein interactions
No full textSYNTHESIS OF PHOTOACTIVABLE PROBES FOR THE STUDY OF GLYCOSPHINGOLIPID-PROTEIN INTERACTIONS
Giuseppina Brasile,1 Federica Compostella,1 Laura Mauri,2Sandro Sonnino2 and Fiamma Ronchetti1
Dipartimento di Chimica, Biochimica e Biotecnologie per la Medicina, Università di Milano
1Via Saldini 50, 20133-Milano, Italy; 2Via Fratelli Cervi 93, 20190- Segrate (Milano), Italy
E-mail:[email protected]
It is widely accepted that glycosphingolipids (GSLs) at the level of the plasma membrane can affect the biological functions of protein molecules, such as cell surface receptors or transporters. The interactions between GSLs and proteins belonging to specific membrane microdomains, called lipid rafts, could be responsible for the modulation of the functional properties of membrane proteins participating in signal transduction. GSL-protein interactions can be investigated by cell photolabelling experiments using radioactive photoactivable GSLs, which yield, when illuminated, a very reactive intermediate that covalently binds to the molecules in the environment, i.e. proteins.1,2
In this context, we have designed a fatty acid probe with two nitrophenylazide photoactivable groups, one at position 2 and the other at the end of the acyl chain. The conjugation of the fatty acid to a radioactive sphingoglycolipid generates a species to be used for photolabelling experiments. In this way, the simultaneous identification of the proteins belonging to both the leaflets of the plasma membrane, the cytoplasmatic and the extracellular one, will be realized.
Herein we describe a general synthetic strategy to obtain not commercially available α,ω-diamino acids, the synthetic precursors of the labelled fatty acids, which we have applied to the synthesis of a C-18 derivative. Furthermore, it will be described the preparation of a photolabelled radioactive GSL as a case study.
1. Aureli M., Prioni S., Mauri L. Loberto N., Casellato R., Ciampa M.G., Chigorno V., Prinetti, A.; Sonnino S. J. Lipid Res. 2010, 51, 798-808
2. Mauri L., Prioni S., Loberto N., Chigorno V., Prinetti A., Sonnino S. Glycoconj. J. 2004, 20, 11-23
Immunology of carbohydrate antigens related to Streptococcus pneumoniae infection : synthesis of a glycolipid construct
No full textCarbohydrates in the form of capsular polysaccharides are the major components on the surface of bacteria, and are important virulence factors of invading bacteria. Immunity against these components confers protection against the infectious disease. However, there are several problems associated to the development of vaccines based on saccharidic antigens. Bacterial polysaccharides are poorly immunogenic T-independent antigens, and they are able to induce only the release of low affinity antibody from B lymphocytes, but not their differentiation.1 The T-lymphocyte independent nature of a polysaccharide may be overcome by conjugating the native or depolymerized polysaccharide to a carrier protein. In a similar way, the conjugation to an immunoadjuvant could lead to a construct able to stimulate a sustainable antibody response. Recently, lipoproteins, i.e. Pam3Cys, have been shown as potent activators of B-lymphocytes and macrophages,2 and thus represent a promising tool for the development of conjugated vaccines.
Herein, the synthesis of a glycoconjugate where the repeating unit of Streptococcus pneumoniae (SP) type 19F capsular polysaccharide is linked to a Pam3CysSer residue through an amino propyl linker will be presented as a case study. The final aim is to evaluate the influence of the lipopeptide on the immune response towards SP, and if antigen specific antibodies can be elicited with low molecular weight conjugates of Pam3CysSer with a saccharide-based hapte
The metabolism of phytosterols in the insect Tenebrio molitor: Utilization of 24-methylenecholesterol and 24,28-epoxymethylenecholesterol
No full text[23,23,25-3H3]24-Methylenecholesterol and the corresponding 24,28-epoxide are converted into labeled cholesterol by larvae of Tenebrio molitor
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