“Click-fluors”: triazole-linked saccharide sensors

A series of boronic acid-containing saccharide receptors was synthesised via copper catalysed azide–alkyne cycloaddition (CuAAC) reactions.</p

Calcium/Calmodulin Dependent Protein Kinase II Bound to NMDA Receptor 2B Subunit Exhibits Increased ATP Affinity and Attenuated Dephosphorylation

Calcium/calmodulin dependent protein kinase II (CaMKII) is implicated to play a key role in learning and memory. NR2B subunit of N-methyl-D-aspartate receptor (NMDAR) is a high affinity binding partner of CaMKII at the postsynaptic membrane. NR2B binds to the T-site of CaMKII and modulates its catalysis. By direct measurement using isothermal titration calorimetry (ITC), we show that NR2B binding causes about 11 fold increase in the affinity of CaMKII for ATPγS, an analogue of ATP. ITC data is also consistent with an ordered binding mechanism for CaMKII with ATP binding the catalytic site first followed by peptide substrate. We also show that dephosphorylation of phospho-Thr286-α-CaMKII is attenuated when NR2B is bound to CaMKII. This favors the persistence of Thr286 autophosphorylated state of CaMKII in a CaMKII/phosphatase conjugate system in vitro. Overall our data indicate that the NR2B- bound state of CaMKII attains unique biochemical properties which could help in the efficient functioning of the proposed molecular switch supporting synaptic memory

An Exciton-Coupled Circular Dichroism Protocol for the Determination of Identity, Chirality, and Enantiomeric Excess of Chiral Secondary Alcohols

Chiral mono-ols are among the most sought after targets in asymmetric synthesis, and therefore, their chemical characterization and associated enantiomeric excess (ee) values are commonly reported. A simple optical method for determining alcohol identity and ee could be widely used. Toward this end, an in situ-generated multicomponent assembly that creates diastereomeric tris(pyridine) metal complexes incorporating chiral secondary alcohols was explored using exciton-coupled circular dichroism (ECCD). Qualitative models were proposed to predict the preferential diastereomer and its twist, and computational studies provided a rationalization of the CD spectra. Different ECCD spectra found for diastereomers formed in the self-assembled tris(pyridine) complexes were used to determine the absolute configurations of chiral mono-ols. Linear discriminant analysis was successfully employed to classify the alcohol analytes, thereby allowing identification of the alcohols. Conformational effects imparted by heteroatoms were also explored, further expanding the substrate scope. Finally, ee calibration curves allowed the determination of the ee of unknown samples of three chiral secondary alcohols with an average error of 3%. The assay described here is unique because no preparation of structurally elaborated chiral hosts is needed