Search Results - (Author, Cooperation:R. M. Jain)

2011-05-28

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Amino Acid Sequence ; Computer Simulation ; Gold ; Metal Nanoparticles ; Models, Molecular ; *Nanotubes, Carbon ; Peptides/*chemistry ; Protein Binding ; Protein Conformation ; *Protein Engineering ; Protein Stability ; Protein Structure, Secondary ; Solubility ; Surface Properties ; Viruses

1572-946X

Flare ; CME ; Post-Eruption Energy Release

Springer Online Journal Archives 1860-2000

Physics

Abstract The powerful cosmic ray flare of Sept. 29, 1989 occurred behind the limb and was observed over a wide spectral range. The analysis of optical, radio, and other relevant data suggest two phases of energy release. After an impulsive phase a prolonged post eruption energy release occurred in an extended region of the corona following the eruption of a large coronal mass ejection (CME). This phase is responsible for numerous coronal and interplanetary phenomena including the ground-level increase of cosmic rays.

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] Fig. 1 Ground-level atmospheric pressure fluctuations at eclipse centre line East Java: a, 9 June; 6, eclipse day, 11 June; c, residual fluctuations, after removing daily tides, during the 11 June 1983 solar eclipse. First to fourth contact times are indicated. Fig. 2 Ground-level atmospheric ...

Electronic Resource

0006-3525

Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

A CD investigation of eleven dehydropeptides is reported. The compounds investigated include tri-, tetra-, hexa-, hepta-, and octapeptides and contain one, two, or three dehydro-phenylalanine (ΔPhe) residues. The peptides showed different CD profiles depending on chain length, position, and number of dehydro residues. The CD data very much complemented that provided by nmr studies, confirming the conformational preference for β-bend structures in small peptides (tripeptides), and 310-helical or α-helical structures in longer peptides. The secondary structures were stable in chloroform solution and were denaturated by addition of trifluoroacetic acid. Solvent titration experiments performed by measuring CD as a function of solvent composition provided evidence that the order →←2 disorder conformational changes occurred as cooperative transitions. © 1996 John Wiley & Sons, Inc.

10 Ill.

Electronic Resource

0006-3525

x-ray diffraction ; crystal structure ; dehydrophenylalanine ; constrained peptides ; 310-helix ; Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

An Nα-protected model pentapeptide containing two consecutive ΔPhe residues, Boc-Leu-ΔPhe-ΔPhe-Ala-Phe-NHMe, has been synthesized by solution methods and fully characterized. 1H-nmr studies provided evidence for the occurrence of a significant population of a conformer having three consecutive, intramolecularly H-bonded β-bends in solution. The solid state structure has been determined by x-ray diffraction methods. The crystals grown from aqueous methanol are orthorhombic, space group P212121, a = 11.503(2), b = 16.554(2), c = 22.107(3) Å, V = 4209(1) Å,3 and Z = 4. The x-ray data were collected on a CAD4 diffractometer using CuKa radiation (λ = 1.5418 Å). The structure was determined using direct methods and refined by full-matrix least-squares procedure. The R factor is 5.3%. The molecule is characterized by a right handed 310-helical conformation (〈φ〉 = -68.2°, 〈ψ〉 = -26.3°), which is made up of two consecutive type III β-bends and one type I β-bend. In the solid state the helical molecules are aligned head-to-tail, thus forming long rod like structures. A comparison with other peptide structures containing consecutive ΔPhe residues is also provided. The present study confirms that the -ΔPhe-ΔPhe-sequence can be accommodated in helical structures. © 1997 John Wiley & Sons, Inc. Biopoly 42: 373-382, 1997

4 Ill.

Electronic Resource

0006-3525

Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

α,β-Dehydro amino acid residues are known to constrain the peptide backbone to the β-bend conformation. A pentapeptide containing only one α,β dehydrophenylalanine (ΔPhe) residue has been synthesized and crystallized, and its solid state conformation has been determined. The pentapeptide Boc-Leu-Phe-Ala-ΔPhe-Leu-OMe (C39H55N5O8, Mw = 721.9) was crystallized from aqueous methanol. Monoclinic space group was P21, a = 10.290(2)°, b = 17.149(2)°, c = 12.179(2) Å, β = 96.64(1)° with two molecules in the unit cell. The x-ray (Mo Kα, λ = 0.7107A) intensity data were collected using a CAD4 diffractometer. The crystal structure was determined by direct methods and refined using least-squares technique. R = 4.4% and Rw = 5.4% for 4403 reflections having |F0| ≥ 3σ(|F0|). All the peptide links are trans and the pentapeptide molecule assumes 310-helical conformation. The mean φ,ψ values, averaged over the first four residues, are -64.4°, -22.4° respectively. There are three 4 → 1 intramolecular hydrogen bonds, characteristic of 310,-helix. In the crystal, the peptide helices interact through two head-to-tail. N—H—O intermolecular hydrogen bonds. The peptide molecules related by 21, screw symmetry form a skewed assembly of helices. © 1995 John Wiley & Sons, Inc.

2 Ill.

Electronic Resource