Search results for "genetics [Cerebellar Neoplasms]"
showing 10 items of 3028 documents
Molecular aggregation in selected crystalline 1:1 complexes of hydrophobicD- andL-amino acids. IV. TheL-phenylalanine series
2009
The amino acid L-phenylalanine has been cocrystallized with D-2-aminobutyric acid, C(9)H(11)NO(2).C(4)H(9)NO(2), D-norvaline, C(9)H(11)NO(2).C(5)H(11)NO(2), and D-methionine, C(9)H(11)NO(2).C(5)H(11)NO(2)S, with linear side chains, as well as with D-leucine, C(9)H(11)NO(2).C(6)H(13)NO(2), D-isoleucine, C(9)H(11)NO(2).C(6)H(13)NO(2), and D-allo-isoleucine, C(9)H(11)NO(2).C(6)H(13)NO(2), with branched side chains. The structures of these 1:1 complexes fall into two classes based on the observed hydrogen-bonding pattern. From a comparison with other L:D complexes involving hydrophobic amino acids and regular racemates, it is shown that the structure-directing properties of phenylalanine closel…
Two pentadehydropeptides with different configurations of the ΔPhe residues
2009
Comparison of the crystal structures of two pentadehydropeptides containing DeltaPhe residues, namely (Z,Z)-N-(tert-butoxycarbonyl)glycyl-alpha,beta-phenylalanylglycyl-alpha,beta-phenylalanylglycine (or Boc(0)-Gly(1)-Delta(Z)Phe(2)-Gly(3)-Delta(Z)Phe(4)-Gly(5)-OH) methanol solvate, C(29)H(33)N(5)O(8) x CH(4)O, (I), and (E,E)-N-(tert-butoxycarbonyl)glycyl-alpha,beta-phenylalanylglycyl-alpha,beta-phenylalanylglycine (or Boc(0)-Gly(1)-Delta(E)Phe(2)-Gly(3)-Delta(E)Phe(4)-Gly(5)-OH), C(29)H(33)N(5)O(8), (II), indicates that the Delta(Z)Phe residue is a more effective inducer of folded structures than the Delta(E)Phe residue. The values of the torsion angles phi and psi show the presence of two …
Conformational studies of the Emp-AKH peptide using Molecular and Langevin Dynamics methods
1998
The secondary structure of the member of the AKH/RPCH family has been studied by Molecular Dynamics and Langevin Dynamics methods. Molecular dynamics simulation were performed in vacuum, model aqueous solution and simulated membrane. Langevin dynamics simulation was performed using the friction factor γ equal to 2 ps-1. Molecular dynamics as well as Langevin Dynamics simulation were conducted at 300 K. All minimum energy conformers have similar backbone structure characterised by the turn consisted out of 3 amino acids, Thr, Pro and Asn7. Structures obtained from Molecular Dynamics simulation are characterised by the lack of hydrogen bonds whereas the structure obtained form Langevin Dynami…
Capillary Rise in Nanotubes Coated with Polymer Brushes
2009
The spontaneous rise of a fluid in a brush-coated nanocapillary is studied by molecular dynamics simulation of a coarse-grained model. The cases of changing wettability of both the capillary walls and the brush were examined. We also investigated the impact of polymer chain length on the transport of fluid along the nanotube. We found that capillary filling takes place in both lyophilic and lyophobic tubes, provided that the polymer brush coating is wetted by the fluid. In all the cases studied, capillary rise proceeds by a time-square law, but the mechanisms behind them (Lucas-Washburn or diffusive propagation) differ, depending on the chain length N. For a wettable wall, the speed of flui…
Cavernolide
2000
Abstract The inhibitory effect of cavernolide, a novel C 21 terpene lactone isolated from the sponge Fasciospongia cavernosa , on PLA 2 and other enzyme activities involved in the inflammatory process was studied. Cavernolide inhibited human synovial sPLA 2 in a concentration-dependent manner with an IC 50 value of 8.8 μM. Besides, this compound decreased in the nanomolar range the myeloperoxidase degranulation process using different stimuli. Cavernolide also inhibited TNFα, NO and PGE 2 production in intact cell experiments. NO and PGE 2 reduction was the consequence of the inhibition on iNOS and COX-2 expression because it did not affect inducible nitric oxide synthase and cyclooxygenase…
In vivo anti-inflammatory activity of saponins from Bupleurum rotundifolium
2001
Seven oleanane-type triterpene saponins were isolated from the methanolic extract of the aerial parts of Bupleurum rotundifolium. They were identified on the basis of their spectral data as 3-O-[alpha-L-rhamnopyranosyl (1--2)-beta-D-glucopyranosyl (1--2)-beta-D-glucopyranosyl]-28-O-[beta-D-glucopyranosyl (1--2)-beta-D-glucopyranosyl] echinocystic acid (saponin 1), 3-O-[alpha-L-rhamnopyranosyl (1--2)-beta-D-glucopyranosyl (1--2)-beta-D-fucopyranosyl] 11-methoxy-primulagenin A (saponin 2), rotundioside E (saponin 3), rotundioside F (saponin 4), 3beta-sulfate, 28-O-[beta-D-glucopyranosyl (1--6)-beta-D-glucopyranosyl (1--2)-beta-D-glucopyranosyl (1--2)-beta-D-glucopyranosyl] ester of primulagen…
7-Amino-2-methylsulfanyl-1,2,4-triazolo[1,5-a]pyrimidine-6-carboxylic acid as the dimethylformamide and water monosolvates at 293 K.
2010
The molecular structure of 7-amino-2-methylsulfanyl-1,2,4-triazolo[1,5-a]pyrimidine-6-carboxylic acid is reported in two crystal environments, viz. as the dimethylformamide (DMF) monosolvate, C(7)H(7)N(5)O(2)S·C(3)H(7)NO, (I), and as the monohydrate, C(7)H(7)N(5)O(2)S·H(2)O, (II), both at 293 (2) K. The triazolo[1,5-a]pyrimidine molecule is of interest with respect to the possible biological activity of its coordination compounds. While the DMF solvate exhibits a layered structural arrangement through N...O hydrogen-bonding interactions, the monohydrate displays a network of intermolecular O...O and N...O hydrogen bonds assisted by cocrystallized water molecules and weak π-π stacking intera…
Relationships between kinetic constants and the amino acid composition of enzymes from the yeast Saccharomyces cerevisiae glycolysis pathway
2012
The kinetic models of metabolic pathways represent a system of biochemical reactions in terms of metabolic fluxes and enzyme kinetics. Therefore, the apparent differences of metabolic fluxes might reflect distinctive kinetic characteristics, as well as sequence-dependent properties of the employed enzymes. This study aims to examine possible linkages between kinetic constants and the amino acid (AA) composition (AAC) for enzymes from the yeast Saccharomyces cerevisiae glycolytic pathway. The values of Michaelis-Menten constant (K M), turnover number (k cat), and specificity constant (k sp = k cat/K M) were taken from BRENDA (15, 17, and 16 values, respectively) and protein sequences of nine…
Bioactivation of the Fungal Phytotoxin 2,5-Anhydro-D-glucitol by Glycolytic Enzymesisan Essential Component of itsMechanism of Action
2002
An isolate of Fusarium solani, NRRL 18883, produces the natural phytotoxin 2,5-anhydro-ᴅ-glucitol (AhG). This fungal metabolite inhibited the growth of roots (I50 of 1.6 mᴍ), butit did nothave any in vitro inhibitory activity. The mechanism of action of AhG requires enzymatic phosphorylation by plant glycolytic kinases to yield AhG-1,6-bisphosphate (AhG-1,6- bisP), an inhibitor of Fru-1,6-bisP aldolase. AhG-1,6-bisP had an I50 value of 570 μᴍ on aldolase activity, and it competed with Fru-1,6-bisP for the catalytic site on the enzyme, with a Ki value of 103 μᴍ. The hydroxyl group on the anomeric carbon of Fru-1,6-bisP is required for the formation of an essential covalent bond to ζ amino fu…
N-(tert-butoxycarbonylglycyl-alpha,beta-dehydrophenylalanylglycylphenylalanyl)-4-nitroaniline.
2000
In the crystal structure of the tetrapeptide Boc0–Gly1–ΔPhe2–Gly3–Phe4–p-NA (p-NA is para-nitroaniline), C33H36N6O8, there are two independent molecules differing in conformation in the asymmetric part of the unit cell. All the amino acids in the peptide are linked trans to each other. The torsion angles in the main chain of both molecules are close to the values of the type β-II turn. Two intramolecular and three intermolecular N—H⋯O hydrogen bonds stabilize the conformation of each of the molecules.