4-Methylumbelliferyl-glycosides as fluorescence probes of sugar-binding sites on lectin molecules: spectral properties and dependence of fluorescence on polarity and viscosity |
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Authors: | M Decastel M Vincent K L Matta J P Frénoy |
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Affiliation: | 1. Biologie Moléculaire des Glycoprotéines, CNRS LA 293, INSERM U 180, UER Biomédicale des Saints-Pères, 45 rue de Saints-Pères, 75006 Paris, France;2. Etats Liés Moléculaires, CNRS ER 64, INSERM U 221, UER Biomédicale des Saints-Pères, Paris, France;3. Department of Gynecologic Oncology, Rosswell Park Memorial Institute, Buffalo, New York, U.S.A. |
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Abstract: | The spectral properties of 4-methylumbelliferyl-glycosides (MeUmb-glycosides) were investigated in order to assess their usefulness as probes of the microenvironment of sugar binding sites on lectin molecules. It was shown that the abnormally high values for fluorescence polarization of free MeUmb-glycosides (from 0.07 to 0.251) were due neither to their molecular size nor to the blockade of their movement, but to the short lifetimes (less than 0.55 ns) of the excited state of these compounds. Working essentially with two MeUmb-monosaccharides and one MeUmb-disaccharide (MeUmb-alpha-D-galactopyranoside, MeUmb-beta-D-galactopyranoside, and MeUmb-2-acetamido-2-deoxy-3-O-(beta-D-galactopyranosyl)-beta-D- galactopyranoside) which were solubilized in various solvents, it was demonstrated that solvent polarity and viscosity definitely affected the fluorescence intensity of MeUmb-glycosides. A low-polarity medium reduced this intensity, and high viscosity enhanced it. The implications of these findings are discussed in relation to the variations in the fluorescence intensity of MeUmb-glycosides when these compounds were bound to lectins. |
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Keywords: | To whom correspondence should be addressed. |
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