Omanische Heilpflanze im Fokus der Phytochemie IPB-Wissenschaftler und Partner aus Dhofar haben jüngst die omanische Heilpflanze Terminalia dhofarica unter die phytochemische Lupe genommen. Die Pflanze ist reich an…
Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
Heuts, D. P. H. M.; Weissenborn, M. J.; Olkhov, R. V.; Shaw, A. M.; Gummadova, J.; Levy, C.; Scrutton, N. S.;Crystal Structure of a Soluble Form of Human CD73 with Ecto-5′-Nucleotidase ActivityChemBioChem132384-2391(2012)DOI: 10.1002/cbic.201200426
CD73 is a dimeric ecto‐5′‐nucleotidase that is expressed on the exterior side of the plasma membrane. CD73 has important regulatory functions in the extracellular metabolism of certain nucleoside monophosphates, in particular adenosine monophosphate, and has been linked to a number of pathological conditions such as cancer and myocardial ischaemia. Here, we present the crystal structure of a soluble form of human soluble CD73 (sCD73) at 2.2 Å resolution, a truncated form of CD73 that retains ecto‐5′‐nucleotidase activity. With this structure we obtained insight into the dimerisation of CD73, active site architecture, and a sense of secondary modifications of the protein. The crystal structure reveals a conserved loop that is directly involved in the dimer‐dimer interaction showing that the two subunits of the dimer are not linked by disulfide bridges. Using biophotonic microarray imaging we were able to confirm glycosylation of the enzyme and show that the enzyme is decorated with a variety of oligosaccharide structures. The crystal structure of sCD73 will aid the design of inhibitors or activator molecules for the treatment of several diseases and prove useful in explaining the possible roles of single nucleotide polymorphisms in physiology and disease.
Publikation
Wehner, J. W.; Weissenborn, M. J.; Hartmann, M.; Gray, C. J.; Šardzík, R.; Eyers, C. E.; Flitsch, S. L.; Lindhorst, T. K.;Dual purpose S-trityl-linkers for glycoarray fabrication on both polystyrene and goldOrg. Biomol. Chem.108919-8926(2012)DOI: 10.1039/C2OB26118A
There is a wide range of immobilisation reactions to tether substrates to a variety of surfaces for array-based analysis. Most of these immobilisation strategies are specific for a particular surface and require an additional linker to be attached to the substrate or the surface. Furthermore, the analysis of functionalised surfaces is often restricted to certain analytical techniques and therefore, different immobilisation strategies for different surfaces are desirable. Here we have tested an S-tritylated linker for non-covalent or covalent immobilisation of mannosides to polystyrene or gold surfaces. S-Tritylated mannosides with varying linkers were readily synthesised and used to add to biorepulsive maleimide-terminated preformed SAMs after in situ deprotection of the S-trityl group. In addition, S-tritylated mannosides themselves formed stable glycoarrays on polystyrene microtiter plates. The glycoarrays were successfully analysed by MALDI-ToF mass spectrometry, SPR spectroscopy, and interrogated with GFP-transfected Escherichia coli cells. This work has shown that a dual purpose linker can be used on multiple surfaces to form arrays allowing for different testing as well as analytical approaches.
Publikation
Šardzík, R.; Green, A. P.; Laurent, N.; Both, P.; Fontana, C.; Voglmeir, J.; Weissenborn, M. J.; Haddoub, R.; Grassi, P.; Haslam, S. M.; Widmalm, G.; Flitsch, S. L.;Chemoenzymatic Synthesis of O-Mannosylpeptides in Solution and on Solid PhaseJ. Am. Chem. Soc.1344521-4524(2012)DOI: 10.1021/ja211861m
O-Mannosyl glycans are known to play an important role in regulating the function of α-dystroglycan (α-DG), as defective glycosylation is associated with various phenotypes of congenital muscular dystrophy. Despite the well-established biological significance of these glycans, questions regarding their precise molecular function remain unanswered. Further biological investigation will require synthetic methods for the generation of pure samples of homogeneous glycopeptides with diverse sequences. Here we describe the first total syntheses of glycopeptides containing the tetrasaccharide NeuNAcα2-3Galβ1-4GlcNAcβ1-2Manα, which is reported to be the most abundant O-mannosyl glycan on α-DG. Our approach is based on biomimetic stepwise assembly from the reducing end and also gives access to the naturally occurring mono-, di-, and trisaccharide substructures. In addition to the total synthesis, we have developed a “one-pot” enzymatic cascade leading to the rapid synthesis of the target tetrasaccharide. Finally, solid-phase synthesis of the desired glycopeptides directly on a gold microarray platform is described.
Publikation
Weissenborn, M. J.; Castangia, R.; Wehner, J. W.; Šardzík, R.; Lindhorst, T. K.; Flitsch, S. L.;Oxo-ester mediated native chemical ligation on microarrays: an efficient and chemoselective coupling methodologyChem. Commun.484444-4446(2012)DOI: 10.1039/C2CC30844D
We report a highly efficient and selective method for the coupling of peptides and glycoconjugates bearing N-terminal cysteines to activated surfaces. This chemoselective method generates stable amide linkages without using any thiol additives.