169 research outputs found
TÔrva TantsumÀe muinaslinnus
http://tartu.ester.ee/record=b2653959~S1*es
MethylÂergometrine maleate from synchrotron powder diffraction data
The title compound {systematic name: 9,10-didehydro-N-[1-(hydroxyÂmethÂyl)propÂyl]-d-lysergamide maleate}, C20H26N3O2
+·C4H3O4
â, contains a large rigid ergolene group. This group consists of an indole plane connected to a six-membered carbon ring adopting an envelope conformation and N-methylÂtetraÂhydroÂpyridine where the methyl group is in an equatorial position. In the crystal, interÂmolecular NâHâŻO, OâHâŻN and OâHâŻO hydrogen bonds form an extensive three-dimensional hydrogen-bonding network, which holds the cations and anions together
1-(2âČ,4âČ-DifluoroÂbiphenyl-4-yl)ethanone
In the crystal structure of the title compound, C14H10F2O, the dihedral angles between the benzene rings in the two crystallographically independent molÂecules are 46.9â
(2) and 47.6â
(2)°. The molÂecules are linked into dimers by CâHâŻF interÂactions and these dimers are further stacked into columns along the b axis by ÏâÏ interÂactions between the benzene rings [centroidâcentroid distance = 3.8221â
Ă
; the dihedral angle between the planes of these rings is 4.87â
(2)°]. In addition, CâFâŻÏ interactions also contribute to the crystal packing (CâŻcentroid distance = 3.5919â
Ă
)
Norleucine, a natural occurrence in a novel ergot alkaloid Îł-ergokryptinine
A novel natural peptide ergot alkaloid γ-ergokryptinine containing norleucine has been isolated from ergot sclerotia of the field-growing parasitic fungus Claviceps purpurea CCM 8059. Its structure was deduced from the NMR and mass spectral data. The final structural proof was provided by the crystal structure determination, which is the first X-ray structure of a natural Nle-containing secondary metabolite. The conformations of three ergopeptinines: γ-ergokryptinine, ergoladinine, and α-ergokryptinine were compared. © Springer-Verlag 2005
Capecitabine from X-ray powder synchrotron data
In the title compound [systematic name 5-deÂoxy-5-fluoro-N-(pentÂyloxycarbonÂyl)cytidine], C15H22FN3O6, the pentyl chain is disordered over two positions with refined occupancies of 0.53â
(5) and 0.47â
(5). The furan ring assumes an envelope conformation. In the crystal, interÂmolecular NâHâŻO hydrogen bonds link the molÂecules into chains propagating along the b axis. The crystal packing exhibits electrostatic interÂactions between the 5-fluoroÂpyrimidin-2(1H)-one fragments of neighbouring molÂecules as indicated by short OâŻC [2.875â
(3) and 2.961â
(3)â
Ă
] and FâŻC [2.886â
(3)â
Ă
] contacts
Mitochondria and Energetic Depression in Cell Pathophysiology
Mitochondrial dysfunction is a hallmark of almost all diseases. Acquired or inherited mutations of the mitochondrial genome DNA may give rise to mitochondrial diseases. Another class of disorders, in which mitochondrial impairments are initiated by extramitochondrial factors, includes neurodegenerative diseases and syndromes resulting from typical pathological processes, such as hypoxia/ischemia, inflammation, intoxications, and carcinogenesis. Both classes of diseases lead to cellular energetic depression (CED), which is characterized by decreased cytosolic phosphorylation potential that suppresses the cellâs ability to do work and control the intracellular Ca2+ homeostasis and its redox state. If progressing, CED leads to cell death, whose type is linked to the functional status of the mitochondria. In the case of limited deterioration, when some amounts of ATP can still be generated due to oxidative phosphorylation (OXPHOS), mitochondria launch the apoptotic cell death program by release of cytochrome c. Following pronounced CED, cytoplasmic ATP levels fall below the thresholds required for processing the ATP-dependent apoptotic cascade and the cell dies from necrosis. Both types of death can be grouped together as a mitochondrial cell death (MCD). However, there exist multiple adaptive reactions aimed at protecting cells against CED. In this context, a metabolic shift characterized by suppression of OXPHOS combined with activation of aerobic glycolysis as the main pathway for ATP synthesis (Warburg effect) is of central importance. Whereas this type of adaptation is sufficiently effective to avoid CED and to control the cellular redox state, thereby ensuring the cell survival, it also favors the avoidance of apoptotic cell death. This scenario may underlie uncontrolled cellular proliferation and growth, eventually resulting in carcinogenesis
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