The Effects of Avidin on Inclusion Phenomena and Fluorescent Properties of Biotin-Appended Dansyl-Modifiedβ-Cyclodextrin

Abstract

Two biotin-appended dansylmodified cyclodextrins 3 and 4 were prepared to examine the effects of avidin binding on guest-inclusion phenomena and fluorescence properties of cyclodextrin derivatives. The fluorescence intensities of hosts 3 and 4 are more than three times larger in the presence of avidin than those in the absence of avidin. The fluorescence lifetime measurements indicate that the dansyl moiety is not exposed to bulk water in the presence of avidin. The longer lifetime component, which newly appears in the presence of avidin, is likely to be that of the dansyl moiety located in the hydrophobic region of avidin. The addition of bile acids such as hyodeoxycholic acid resulted in decreases in the fluorescence intensities of 3 and 4 in accordance to the extrusion of the dansyl moiety from the hydrophobic cyclodextrin cavity to bulk water. Similar guest-induced decreases in the fluorescence intensity were observed for 3 in the presence of avidin, but under the same conditions the decreases are smaller for 4. On the other hand, the binding constants of 3 and 4 became larger in the presence of avidin. All these results demonstrate that avidin perturbs the inclusion phenomena and fluorescence properties of 3 and 4 by providing a hydrophobic environment around the host cavity.

RuIII Complexes for Anticancer Therapy: The Importance of Being Nucleolipidic

“…The lipophilic (oleic acid) and hydrophilic [hexakis(ethylene glycol)] appendages were attached through ester linkages, chemically stable but easily cleavable in vivo by esterase-mediated degradation, in analogy with previously studied systems. [130][131][132][133][134][135][136] The synthesis of HoThyDansRu was accomplished in nine steps starting from uridine. In addition, dansyl-based probes are very sensitive to solvent polarity conditions, thus providing relevant information on their local environments.…”

“…In addition, dansyl-based probes are very sensitive to solvent polarity conditions, thus providing relevant information on their local environments. [130][131][132][133][134][135][136] The synthesis of HoThyDansRu was accomplished in nine steps starting from uridine. The first step (Scheme 7) involved the regioselective protection of the 3′-and 5′-hydroxy groups of the starting nucleoside, for successive attachment of the fluorescent label specifically in the 2′-OH position.…”

pH Dependent In−Out Isomerism of an Amino-β-cyclodextrin Derivative

“…These complexes have important applications since when the pendant group is a fluorophore, they can be used as chemosensors. [26][27][28][29][30][43][44][45][46][47][48][49] The two processes (inter/intra) compete with each other, and one of them must be avoided if the other one is desired.…”

Cyclodextrin Dimers as Receptor Molecules for Steroid Sensors

“…[12] Ueno and co-workers have used biomolecules as large caps for cyclodextrin-based sensing molecules. Thus, cyclodextrin derivatives with monensin moieties, [13] or biotin-modified cyclodextrins that interact with avidin, [14] were investigated as receptors with an enlarged hydrophobic cavity.…”

“…The cooperatively bound 1 b is detected by 9 with comparable selectivity to 1 d. In contrast, both monomeric bcyclodextrin receptors [13,14,33] and the dimer, which is connected through the primary side [21] and lacks the possibility of cooperative binding of bile salts, show a strong preference for 1 d.…”