ABSTRACT
Carbohydrate-protein binding is a supramolecular recognition process that underpins myriad biological events. However, the precise conformational and configurational requirements for biomolecular recognition are often poorly understood, since such phenomena often occur in a strongly spatiotemporal manner. Photoswitchable glycoconjugates have emerged as promising investigational tools for probing carbohydrate-protein recognition and for controlling bacterial adhesion. Reversible photoisomerisation, in particular that of azobenzene glycoconjugates, has also been exploited as a promising strategy for controlling supramolecular self-assembly and macroscopic properties, thereby facilitating the development of light responsive carbohydrate-based materials. The following review will highlight the recent advances in the design and applications of photoswitchable glycoconjugates, paying particular attention to the application of light as a stimulus for modulating protein and cellular adhesion, amphiphilicity and supramolecular assembly of carbohydrate-based materials.
Subject(s)
Glycoconjugates/chemical synthesis , Glycoconjugates/radiation effects , Light , Azo Compounds/chemistry , Glycoconjugates/chemistry , Photochemical ProcessesABSTRACT
Methods to transform carbohydrates are often complex and tedious, both due to the vast array of naturally occurring and synthetically designed scaffolds which may manifest meager to drastic reactivity, dependent upon the transformation sought and the stereogenic site chosen. In order to facilitate and expedite desired synthetic transformation, many researchers are utililizing microwave and ultrasonic irradiation to achieve their goals, in generally high yields within a shorter period of time, and often without undesirous byproducts. The basic physical principles underlying the energy regimes are qualitatively discussed prior to review of the applications in carbohydrate syntheses and transformation. This literature review looks at research involving glycosylations, -OH group conversions, isotopic incorporation, and C-N bond formation. Instances of improved yields and selectivities resultant from the use of these high-energy sources will be highlighted.
Subject(s)
Carbohydrates/chemical synthesis , Carbohydrates/radiation effects , Energy Transfer , Glycoconjugates/chemistry , Glycoconjugates/radiation effects , Microwaves , Ultrasonics , Carbohydrates/chemistry , Glycoconjugates/chemical synthesisABSTRACT
Irradiation of the murine fetal inner ear is known to produce damage both to the vestibular and cochlear parts in the adult mouse. Fluorescein-labelled lectins were used to reveal possible differences in the glycoconjugate content between normal and irradiated inner ears. In the vestibular part, the otoconia showed the highest uptake of labelled sugars. This uptake was weaker after irradiation when compared to non-irradiated specimens. The type I hair cells in the ampulla and in the utricle showed a weaker uptake, but no labelling was demonstrated in the type II hair cells compared to the non-irradiated controls. In the cochlear part of the inner ear almost no uptake of fluorescent-binding lectins could be demonstrated in the irradiated groups except for in the tectorial membrane. In the endolymphatic sac no uptake was shown after prenatal irradiation. These findings are discussed and correlated to the already known damage of the inner ear following prenatal irradiation.
