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Induction of apoptosis by synthetic ceramide analogues in the human keratinocyte cell line HaCaT (1998)

Bektas, M. ; Dullin, Y. ; Wieder, T. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Experimental dermatology 7 (1998), S. 0

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ISSN: 1600-0625

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Medicine

Notes: Abstract: In contrast to extracellular, long chain ceramides which comprise a structural component of the epidermal water barrier, intracellular ceramides originating from sphingomyelin hydrolysis have been shown to inhibit proliferation and to induce apoptosis in different cell populations. To further elucidate the possible role of intracellular ceramides in human epidermis, two new cell-permeable ceramide analogues, N-thioacetylsphingosine (C2-Cer=S) and 4-dodecanoylamino-decan-5-ol (FS-5), were synthesized and tested for their ability to suppress cell growth and to induce apoptosis in immortalized human keratinocytes. It was shown that the well-investigated ceramide analogue N-acetylsphingosine (C2-Cer=O), as well as the new compound C2-Cer=S inhibited proliferation of HaCaT cells with half-inhibitory concentrations (IC50) of 20 μg/ml and 10 μg/ml, respectively, whereas FS-5 has been potent with an IC50〉40 μg/ml. Overall, all three ceramide analogues induced apoptosis in HaCaT cells as assessed by DNA-fragmentation using ELISA technique and in situ nick end labelling, thereby confirming the importance of ceramide signalling in keratinocytes.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1600-0625.1998.tb00334.x

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Enzymatic transfer of sialic acids modified at C-5 employing four different sialyltransferases (1995)

Groß, H. J. ; Brossmer, R.

Springer

Glycoconjugate journal 12 (1995), S. 739-746

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ISSN: 1573-4986

Keywords: sialic acid analogues ; CMP-glycosides ; sialyltransferases ; resialylation

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract We present kinetic studies on the enzymatic transfer of several synthetic sialic acid analogues, modified at C-5, to distinct glycoprotein glycans by sialytransferases differing in acceptor- and linkage-specificity. Biochemical properties of sialic acids were modified by introducing formyl-, trifluoroacetyl-, benzyloxycarbonyl-, and aminoacetyl-groups to the amino group at C-5 of neuraminic acid. The latter substitution renders the corresponding α-glyocoside resistant towards sialidases. The respective CMP-sialic acid analogues were prepared by CMP-sialic acid synthase with a yield of 13–55%. The kinetic parameters of several sialyltransferases for the 5-substituted CMP-glycosides differed significantly. Relative to parent CMP-NeuAc, reaction rates of human- and rat liver Galβ1, 4GlcNAc α2,6-sialyl-transferases ranged from 50 to 170%, of GalNAc α2,6-sialyltransferases from 40–140%, and of Galβ1,3Gal-NAc α2,3-sialyltransferase from 20–50%. Resialylation of asialo-α1-acid glycoprotein by 5-N-formyl- and 5-N-aminoacetyl-neuraminic acid employing rat liver Galβ1,4GlcNAc α2,6-sialyltransferase proceeded to about 80% of galactose sites which is identical to the extent achieved with parent NeuAc. According to our data, neosialoglycoconjugates which carry sialic acids modified at theN-acetyl group can be prepared for structure-function analysis, as this position seems crucial for recognition of adhesion proteins and influenza viruses.