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[en] Alternatively spliced β-neurexins (β-NRXs) and neuroligins (NLs) are thought to have distinct extracellular binding affinities, potentially providing a β-NRX/NL synaptic recognition code. We utilized surface plasmon resonance to measure binding affinities between all combinations of alternatively spliced β-NRX 1-3 and NL 1-3 ectodomains. Binding was observed for all β-NRX/NL pairs. The presence of the NL1 B splice insertion lowers β-NRX binding affinity by 2-fold, while β-NRX splice insertion 4 has small effects that do not synergize with NL splicing. New structures of glycosylated β-NRXs 1 and 2 containing splice insertion 4 reveal that the insertion forms a new β strand that replaces the β10 strand, leaving the NL binding site intact. This helps to explain the limited effect of splice insert 4 on NRX/NL binding affinities. These results provide new structural insights and quantitative binding information to help determine whether and how splice isoform choice plays a role in β-NRX/NL-mediated synaptic recognition.
[en] The humane transferrin is responsible for the transport of iron in the body and has strong affinity with tetravalent plutonium. Affinity is characterized by a parameter called complexation constant. In 1991 it was concluded that transferrin affinity for plutonium was similar to that for iron but this result needed experimental backing that was impossible to get at that time. The coupling between capillary electrophoresis and mass spectroscopy has shown that the complexation constant between transferrin and plutonium is 10.000 times more important than that between transferrin and iron. (A.C.)
[en] We classify regular subalgebras of Kac-Moody algebras in terms of their root systems. In the process, we establish that a root system of a subalgebra is always an intersection of the root system of the algebra with a sublattice of its root lattice. We also discuss applications to investigations of regular subalgebras of hyperbolic Kac-Moody algebras and conformally invariant subalgebras of affine Kac-Moody algebras. In particular, we provide explicit formulae for determining all Virasoro charges in coset constructions that involve regular subalgebras
[en] It has been shown that calculating atomic charges using quantum mechanical level theory greatly improves the accuracy of docking. A protocol was developed and shown to be effective. That this protocol works is just a manifestation of the fact that electrostatic interactions are important in protein-ligand binding. In order to investigate how the same protocol helps in prediction of binding affinities, we took a series of known cocrystal structures of influenza neuraminidase inhibitors with the receptor and performed docking with Glide SP, Glide XP, and QPLD, the last being a workflow that incorporates QM/MM calculations to replace the fixed atomic charges of force fields with quantum mechanically recalculated ones at a given docking pose, and predicted the binding affinities of each cocrystal. The correlation with experimental binding affinities considerably improved with QPLD compared to Glide SP/XP yielding r2 = 0.83. The results suggest that for binding sites, such as that of neuraminidase, which are laden with hydrophilic residues, protocols such as QPLD which utilizes QM-based atomic charges can better predict the binding affinities
[en] Highlights: • Crucial influence of open-closed skeletal transitions on the electronic properties of fullerene was demonstrated. • Electrochemically promoted switching of electronic properties based on disruption of the conjugated 62π-electron system into the isolated 32 and 28π-electron fragments upon closing the [5,6]-bond in question. • Regioselective near-equatorial cycloproponation of trifluoromethylfullerene Cs-C70(CF3)8 was elaborated. • More compact alternatives promising molecular switching capabilities can be found within the family of pyramidalized polyenes. - Abstract: Despite trifluoromethylfullerene Cs-C70(CF3)8 has a multitude of available reaction sites, [2 + 1] cycloaddition of CX2 moieties (X = F and p-MeOC6H4) proceeds regioselectively at a particular [5,6]-bond. Depending on the nature of X, the resulting derivative can be either [5,6]-open (i.e., the said C−C bond is cleaved) or [5,6]-closed, and this structural detail, seemingly insignificant for a molecule that large, brings about a remarkable 0.6 eV difference in the electron affinity, as revealed by electrochemical studies. Synthesis, structural and electrochemical elucidation of the C70(CF3)8(CX2) compounds are discussed, as well as electrochemically promoted switching of the electronic properties based on disruption of the conjugated 62π-electron system into the isolated 32 and 28π-electron fragments upon closing the [5,6]-bond.
[en] Electron affinities are calculated in the form of linear functions of the degree of hexagonality by two different methods using the concept of band offsets in heterojunctions formed by 3C-SiC in contact with a non-cubic polytype
[en] Data published in recent years on the synthesis of serotonin 5-HT_6 receptor modulators are summarized. Modulators with high affinity for 5-HT_6 receptors exhibiting different degrees of selectivity — from highly selective to semiselective and multimodal — are described. Clinical trial results are reported for the most promising serotonin 5-HT_6 receptor modulators attracting special attention of medicinal chemists. The bibliography includes 128 references