Antifungal bioactivity-guided fractionation of the organic extract of the sponge Polymastia boletiformis, collected from the west coast of Ireland, led to the isolation of two new sulfated steroid-amino acid conjugates (1 and 2). Extensive 1D and 2D NMR analyses in combination with quantum mechanical calculations of the electronic circular dichroism (ECD) spectra, optical rotation, and 13C chem...

The recurrent neural network is a feed-forward network ascribed to a parent neural network with feed-back connections (or in another term, oriented cycles). Its adaptation is performed by an analog of the standard back-propagation adaptation method. The recurrent neural network approach is illustrated by prediction and classification of 13C NMR chemical shifts in a series of monosubstituted ben...

The MutT protein, a 129-residue enzyme from Escherichia coli which prevents A.T-->C.G mutations, catalyzes the hydrolysis of nucleoside triphosphates (NTP) to nucleoside monophosphates (NMP) and pyrophosphate [Bhatnagar, S. K., Bullions, L. C., & Bessman, M. J. (1991) J. Biol. Chem. 266, 9050-9054], by a mechanism involving nucleophilic substitution at the rarely attacked beta-phosphorus of NTP...

The incorporation of cholesteryl oleate and triolein into phospholipid vesicles was studied in cosonicated mixtures of 94 weight % egg phosphatidylcholine and 6 weight % neutral lipid (0-6% triolein and 6-0% cholesteryl oleate). 13C NMR spectroscopy was used to quantitate both neutral lipids in vesicles containing 90% isotopically substituted [carbonyl-13C]cholesteryl oleate and [carbonyl-13C]t...

13C NMR spectroscopic investigations were conducted for various amino acid derivatives and peptides. It was observed that chemical shifts of the carbonyl carbons are correlated with solvent polarities, but extent depends on structures. The size functional groups inter- intra-molecular hydrogen bonding appear to be major contributors this tendency.

some of the adamantane properties were calculated in this study. chemical shift, free energy ofsolvation, free energy of cavity formation, henry's law constant, and other properties ofadamantane in dry phase, three solvents and three temperatures have been calculated with abinitio method base on density functional theory (dft) at b3lyp/6-31g, b31yp/6-31g*, b3lyp/6-31+g* and b3lyp/6-31++g** leve...

Transition metal hydrides are of great interest in chemistry because of their reactivity and their potential use as catalysts for hydrogenation. Among other available techniques, structural properties in transition metal (TM) complexes are often probed by NMR spectroscopy. In this paper we will show that it is possible to establish a viable methodological strategy in the context of density func...

The electronic structure of the primary electron acceptor, bacteriopheophytin a (A), in photosynthetic reaction centers (RCs) of the purple bacterium Rhodobacter (R.) sphaeroides is investigated by photochemically induced dynamic nuclear polarization (photo-CIDNP) magic-angle spinning (MAS) NMR spectroscopy. Uniformly labelled RCs have been prepared for these experiments, by adding the u-13C4-...

The structure of the ortho-, meta- and para- hybrid diindolylmethane-phenylboronic acids and their interactions were optimized with by a quantum chemical method, using density functional theory at the (DFT) level. Thus, infrared bands were assigned based on the scaled theoretical wavenumbers by correlating the respective experimental data of the molecules. In addition, the corresponding ¹H-/13C...