Interaction of Fusarium solani lectin with monosaccharides and oligosaccharides: a fluorometric study

The intrinsic fluorescence intensity of Fusarium solani lectin was quenched upon binding to mono- and oligosaccharides without any change in the emission maximum and it was used to determine association constants for several sugars and glycans. The lectin interacted very poorly with monosaccharides but well with disaccharides (T-antigen and LacNAc) with a distinction between beta1-->4 and beta1-->3 linkages. Among the monosaccharides, the interaction was observed only with Gal/GalNAc derivatives and not with Glc/Man derivatives. Thermodynamic studies revealed that the binding of the lectin with all the saccharides is enthalpically driven and exothermic in nature. Asialo-triantennary N-glycan and asialo-biantennary N-glycan showed higher affinity than monovalent LacNAc with significant increase in binding enthalpy, pointing towards the importance of multivalency in the lectin-ligand interactions. Time-resolved fluorescence measurement indicated the lectin has two lifetimes for tryptophan and the shorter lifetime is affected on ligand binding.     

Room-temperature biosynthesis of ferroelectric barium titanate nanoparticles

The syntheses of inorganic materials by biological systems is characterized by processes that occur close to ambient temperatures, pressures, and neutral pH, as is exemplified by biosilicification and biomineralization processes in nature. Conversely, laboratory-based syntheses of oxide materials often require extremes of temperature and pressure. We have shown here the extracellular, room-temperature biosynthesis of 4-5 nm ternary oxide nanoparticles such as barium titanate (BT) using a fungus-mediated approach. The tetragonality as well as a lowered Curie transition temperature in sub-10 nm particles was established, and the ferroelectricity in these particles was shown using Kelvin probe microscopy.