1,721,626 research outputs found
The peptide 310-helix: Historical background and recent structural studies and applications
No full textBiological role of D-alpha-amino acids and their occurrence in foodstuffs
No full textIn this paper we review the current understanding of biological and physiological
role of D-a-amino acids and the significance of their presence in foodstuffs. The importance
of the 19 L-a-amino acids used as building blocks of proteins it is well-known, but the
biological role of their D-enantiomers in the body has to be further adequately clarified.
Today it is well established the presence of D-a-amino acids in microorganisms, plants,
lower animals, mammalian and humans. In food products, D-a-amino acids are generated
from L-a-amino acids via racemization depending on the processing procedures or the
use/presence of microorganisms when fermentation occurs
Uncommon, but emerging, alpha-peptide conformations
No full textCompared with the classical secondary structural elements of proteins [a-helix, p-pleated sheets, isolated P-turns, and Poly(Pro)(n) helix] other types of helical conformations [3(10)-helix and p-turn ribbon spiral, gamma-helix, and 2.0(5)-helix] of peptides based on a-amino acids are currently emerging particularly from detailed analyses of appropriately designed model compounds. Their 3D-structural characterizations offer fascinating issues of precise control of probe -probe distances and relative orientations. Therefore, they present real potential to play a significant role as rigid, but easily tunable, spacers and templates in various areas of organic chemistry, supramolecular chemistry, and physical chemistry
Understanding alpha-amino acid chemistry from x-ray diffraction structures
No full textThe geometry and conformation for a variety of reactive or-amino acid and peptide derivatives, as obtained from x-ray diffraction analyses, are reviewed in detail. The derivatives are (a) carboxylic acid halides, (b) anhydrides, (c) esters, (d) azides, and (e) amides. The contribution of this information to our understanding of amino acid reactivity, regiospecificity, and tendency to racemization is discussed. (C) 1997 John Wiley & Sons, Inc
TOAC, a nitroxide spin-labeled, achiral C(alpha)-tetrasubstituted alpha-amino acid, is an excellent tool in material science and biochemistry
No full textThe 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid is a nitroxide spin-labeled, achiral C(alpha)-tetmsubstituted alpha-amino acid that has recently been shown to be an effective beta-turn and 3(10)/alpha-helix inducer in peptides and an excellent and relatively rigid electron spin resonance probe and fluorescence quencher. (C) 1998 John Wiley & Sons, Inc
An oxazol-5(4H)-one from benzyloxycarbonyl-(Aib)4-OH
No full textBenzyl N-[8-(4,4-dimethyl-5-oxo-4,5-dihydrooxazol-2-yl)-2,5,5,8-tetramethyl-3,6-dioxo-4,7-diazanon-2-yl]carbamate, C24H34N4O6, an oxazol-5(4H)-one from N-alpha-benzyloxycarbonyl-(Aib)(4)-OH (Aib = alpha-aminoisobutyryl) represents the longest peptide oxazolone so far characterized by X-ray diffraction. The overall geometry of the oxazolone ring compares well with literature data. The Aib(1) and Aib(2) residues are folded into a type III beta-bend, while the conformation adopted by Aib(3), preceding the oxazolone moiety, is semi-extended. The disposition of the oxazolone ring relative to the preceding residue is stabilized by C-H ... N and C-H ... O intramolecular interactions
Electronic and Vibrational Signatures of Peptide Helical Structures: A Tribute to Anton Mario Tamburro
No full textOur efforts on the synthesis of peptides with well-characterized secondary structures, combined with detailed spectroscopic investigations, most of them performed in collaboration with internationally recognized experts, have allowed us to publish the electronic (electronic circular dichroism) and vibrational (FTIR absorption, vibrational circular dichroism, Raman, and Raman optical activity) signatures of the poorly studied peptide 3(10)-helix (and the related beta-bend ribbon spiral conformation as well) in comparison with those already known for the classical alpha-helix
Peptidomimetics.
No full textTopic: Synthetic Molecules as Tools for Chemical Biology, Synthetic Proteins to Explore Biology
High-resolution Solid-state C-13-nmr of Peptides - A Study of Chain-length Dependence For 310-helix Formation
No full textTotal syntheses in solution of TOAC-labelled alamethicin F50/5 analogues
No full textTotal syntheses in solution of a set of four selected analogues of the 19-mer component F50/5 of alamethicin, the most extensively studied among the channel-former peptaibol antibiotics, are planned and reported. All analogues bear three Glu(OMe) residues, replacing the Gln residues at positions 7, 18, and 19 of the naturally occurring compound. Three analogues are mono-labelled with the free-radical-containing amino acid residue TOAC at the strategic positions 1, 8, or 16. The fourth analogue is bis-labelled with the same EPR-active residue at both positions 1 and 16. In the native sequence, all of the positions where TOAC replacements have been introduced are characterized by residues of Aib, the prototype of the class of helicogenic Cα-tetrasubstituted α-amino acids. All of the TOAC analogues synthesized exhibit significant membrane-modifying properties
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