Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0162871 (abdominal aortic aneurysm)
 8,664 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to test the helical preference of short oligo-L-leucines, we crystallized the tripeptide L-leucyl-L-leucyl-L-leucine (LLL) and carried out x-ray diffraction studies of it (L-leucyl-L-leucyl-Lleucine)2. 3CH3OH. H2O, (C39H84N6O12), crystallized in the monoclinic system, space group P2(1), cell parameters: a = 12.031(2), b = 15.578(3), c = 14.087(2) A, alpha = 90 degrees, beta = 97.29(1) degrees, gamma = 90 degrees, V = 2618.6 A3, MW = 829.1, Dc = 1.051 g cm-3, R index of 0.057 for 4213 reflections (lambda CuK alpha = 1.5418 A) > 2 sigma. LLL takes up the beta-sheet rather than a helical conformation in the crystalline state. The three methanol molecules and the water molecule that constitute the solvent of crystallization form a network of hydrogen bonds to the LLL molecules and to one another. It is rather remarkable that though A and L have stronger helical preferences than G, neither AAA nor LLL form the crystalline helix but GAL does, indicating that the helical preferences depend on the sequence context. The residue L2 in molecule A and the residues L1 and L3 of molecule B do not show the preferred conformation for forming helices. Further, very remarkably, LLL exhibits a unique supersecondary feature of the protein folding topology, namely the twisted beta-sheet, whereas most short peptides show only the classical beta-sheet conformation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Crystal structure and a twisted beta-sheet conformation of the tripeptide L-leucyl-L-leucyl-L-leucine monohydrate trimethanol solvate: conformation analysis of tripeptides. 757 52

Methyl ricinoleate (1) was treated with bromine and the dibromo derivative (2) was reacted with ethanolic KOH under ultrasonic irradiation to give 12-hydroxy-octadec-9-ynoic acid upon acidification with dil. HCI. The latter compound was methylated with BF3/methanol to give methyl 12-hydroxy-octadec-9-ynoate (3). Compound 3 was treated with methanesulfonyl chloride in the presence of triethylamine in CH2Cl2 to give methyl 12-mesyloxy-octadec-9-ynoate (4). Reaction of methyl 12-mesyloxy-octadec-9-ynoate with aqueous KOH under ultrasonic irradiation (20 kHz) gave (11E)-octadecen-9-ynoic acid (5, santalbic acid, 40%) and (11Z)-octadecen-9-ynoic acid (6, 60%) on acidification with dil. HCI. These isomers were separated by urea fractionation. The 13C nuclear magnetic resonance (NMR) spectroscopic properties of the methyl ester and the triacylglycerol (TAG) esters of these enynoic fatty acid isomers were studied. The carbon shifts of the unsaturated carbon nuclei of the methyl ester of the E-isomer were unambiguously assigned as 88.547 (C-9), 79.287 (C-10), 109.760 (C-11), and 143.450 (C-12) ppm, while the unsaturated carbon shifts of the (Z)-enynoate isomer appeared at 94.277 (C-9), 77.561 (C-10), 109.297 (C-11), and 142.668 (C-12) ppm. In the 13C NMR spectral analysis of the TAG molecules of type AAA containing either the (Z)- or (E)-enyne fatty acid, the C-1 to C-6 carbon atoms on the alpha- and beta-acyl positions were differentiated. The unsaturated carbon atoms in the alpha- and beta-acyl chains were also resolved into two signals except that of the C-11 olefinic carbon. Sandal (Santalum album) wood seed oil (a source of santalbic acid) was separated by silica chromatography into three fractions. The least polar fraction (7.2 wt%) contained TAG which had a random distribution of saturated and unsaturated fatty acids, of which oleic acid (69%) was the predominant component. The second fraction (3.8 wt%) contained santalbic acid (58%) and oleic acid (28%) together with some other normal fatty acids. Santalbic acid in this fraction was found in both the alpha- and beta-acyl positions of the glycerol "backbone." The most polar fraction (89 wt%) consisted of TAG containing santalbic acid only. The distribution of the various fatty acids on the glycerol "backbone" was supported by the results from the 13C NMR spectroscopic analysis.
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PMID:Ultrasound-assisted synthesis of santalbic acid and a study of triacylglycerol species in Santalum album (Linn.) seed oil. 889 8

Two interacting AAA ATPases, Pex1p and Pex6p, are indispensable for peroxisome biogenesis in different organisms. Mutations affecting corresponding genes are the most common cause of the peroxisome biogenesis disorders in humans. By UV mutagenesis of the Hansenula polymorpha pex6 mutant, deficient in peroxisome biogenesis, we isolated a conditional cold-sensitive strain with restored ability to grow in methanol medium at 37 degrees C but not at 28 degrees C. Sequencing of the pex6 allele revealed a point mutation in the first AAA module of the PEX6 gene that leads to substitution of a conserved amino acid residue (G737E). An additional intragenic mutation identified in the cold-sensitive pex6 allele leads to a conserved amino acid substitution in the second AAA domain (R1000G). Electron microscopic analysis revealed restored peroxisomes in methanol-induced cold-sensitive pex6 cells at both permissive and restrictive temperatures. If separated, the secondary mutation did not affect methylotrophic growth. Our data suggest that H. polymorpha Pex6p may have a complex function in peroxisome biogenesis in which identified amino acid residues are involved.
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PMID:Identification of intragenic mutations in the Hansenula polymorpha PEX6 gene that affect peroxisome biogenesis and methylotrophic growth. 1461 78

The results from an experimental study of bare and microsolvated peptide monocations in high-energy collisions with cesium vapor are reported. Neutral radicals form after electron capture from cesium, which decay by H loss, NH(3) loss, or N-C(alpha) bond cleavage into characteristic z(*) and c fragments. The neutral fragments are converted into negatively charged species in a second collision with cesium and are identified by means of mass spectrometry. For protonated GA (G = glycine, A = alanine), the branching ratio between NH(3) loss and N-C(alpha) bond cleavage is found to strongly depend on the molecule attached (H(2)O, CH(3)CN, CH(3)OH, and 18-crown-6 ether (CE)). Addition of H(2)O and CH(3)OH increases this ratio whereas CH(3)CN and CE decrease it. For protonated AAA ([AAA+H](+)), a similar effect is observed with methanol, while the ratio between the z(1) and z(2) fragment peaks remains unchanged for the bare and microsolvated species. Density functional theory calculations reveal that in the case of [GA+H](+)(CE), the singly occupied molecular orbital is located mainly on the amide group in accordance with the experimental results.
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PMID:Electron-capture-induced dissociation of microsolvated di- and tripeptide monocations: elucidation of fragmentation channels from measurements of negative ions. 1926 30

The objective of this study was to develop instant thin-layer chromatography (ITLC) conditions for the determination of radiochemical purity of 68Ga-DOTATATE in a shorter time period than those stated in the NETSPOT (Advanced Accelerator Applications, Saint-Genis-Pouilly, France; AAA) kit package insert (PI). A faster ITLC system is needed to reduce the 48- to 50-min development time so that more radioactivity is available for single patient use and wait times are shorter in the event of kit failure. Methods: Variations of the PI mobile system were evaluated with microfiber chromatography paper impregnated with silica gel (ITLC-SG). After a more suitable mobile system was identified, evaluation began by attempting to shorten the 10-cm development distance to 7, 8, and 9 cm. Results: Experiments using variations of PI mobile phase showed that increasing the proportion of methanol in the mobile phase decreased development time. Additionally, if the ratio of 1 M ammonium acetate was reduced to 10% or less, retention factor values fall outside specification. Reducing the development distance shortened development time as expected; however, it also affected the resolution aspect of the radiochromatogram. Conclusion: The fastest developing ITLC system, which maintained resolution and peak shape, was methanol:1 M ammonium acetate (80:20 V/V) with ITLC-SG using a development distance of 8 cm.
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PMID:Rapid Instant Thin-Layer Chromatography System for Determining the Radiochemical Purity of 68Ga-DOTATATE. 2972 7