scholarly journals Helical structures of l-Leu-based peptides having chiral six-membered ring amino acids

Tetrahedron ◽  
2016 ◽  
Vol 72 (22) ◽  
pp. 3124-3131 ◽  
Author(s):  
Tomohiro Umeno ◽  
Atsushi Ueda ◽  
Makoto Oba ◽  
Mitsunobu Doi ◽  
Takayuki Hirata ◽  
...  
Keyword(s):  
Amino Acids ◽  
Membered Ring ◽  
Helical Structures

Tropolone-Based Treatments for Visualising Latent Fingermarks on Porous Surfaces

2019 ◽  
Author(s):  
Clara M. Agapie ◽  
Melissa Sampson ◽  
William Gee
Keyword(s):  
Amino Acids ◽  
Uv Radiation ◽  
Membered Ring ◽  
Diazonium Salts ◽  
Chemical Detection ◽  
Latent Fingerprints ◽  
Porous Surfaces

The work describes a new chemical means of visualising latent fingerprints (fingermarks) using tropolone. Tropolone reacts with amino acids within the fingermark residue to form adducts that absorb UV radiation. These adducts provide useful contrast on highly-fluorescent prous surfaces will illuminated with UV radiation. The conjugated seven-membered ring of the tropolone adduct can be reacted further diazonium salts, which is demonstrated here with formation of two dyes. The methodology is extremely rapid, occurring in minutes with mild heating, and can be applied before ninhydrin in a chemical detection sequence. <br>

ChemInform Abstract: Synthesis of New Seven-Membered Ring Cyclic Dipeptides from Functionalized β-Amino Acids.

ChemInform ◽  
2010 ◽  
Vol 31 (14) ◽  
pp. no-no
Author(s):  
Ouafaa El Mahdi ◽  
Jean-Pierre Lavergne ◽  
Jean Martinez ◽  
Philippe Viallefont ◽  
E. M. Essassi ◽  
...  
Keyword(s):  
Amino Acids ◽  
Membered Ring ◽  
Cyclic Dipeptides

Nonstandard Amino Acids in Conformational Design of Peptides. Helical Structures in Crystals of 5-10 Residue Peptides Containing Dipropylglycine and Dibutylglycine

1994 ◽  
Vol 116 (23) ◽  
pp. 10355-10361 ◽  
Author(s):  
Isabella L. Karle ◽  
R. Balaji Rao ◽  
Sudhanand Prasad ◽  
Ramesh Kaul ◽  
P. Balaram
Keyword(s):  
Amino Acids ◽  
Helical Structures

Cell-Penetrating Helical Peptides Having l-Arginines and Five-Membered Ring α,α-Disubstituted α-Amino Acids

2014 ◽  
Vol 25 (10) ◽  
pp. 1761-1768 ◽  
Author(s):  
Takuma Kato ◽  
Makoto Oba ◽  
Koyo Nishida ◽  
Masakazu Tanaka
Keyword(s):  
Amino Acids ◽  
Membered Ring ◽  
Helical Peptides ◽  
Cell Penetrating

scholarly journals The cDNA-deduced amino acid sequence for trichohyalin, a differentiation marker in the hair follicle, contains a 23 amino acid repeat.

1990 ◽  
Vol 110 (2) ◽  
pp. 427-436 ◽  
Author(s):  
M J Fietz ◽  
R B Presland ◽  
G E Rogers
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Intermediate Filament ◽  
Tandem Repeats ◽  
Single Copy ◽  
Hair Follicles ◽  
Helical Structures ◽  
Differentiation Marker ◽  
Carboxy Terminal

Trichohyalin is a highly expressed protein within the inner root sheath of hair follicles and is similar, or identical, to a protein present in the hair medulla. In situ hybridization studies have shown that trichohyalin is a very early differentiation marker in both tissues and that in each case the trichohyalin mRNA is expressed from the same single copy gene. A partial cDNA clone for sheep trichohyalin has been isolated and represents approximately 40% of the full-length trichohyalin mRNA. The carboxy-terminal 458 amino acids of trichohyalin are encoded, and the first 429 amino acids consist of full- or partial-length tandem repeats of a 23 amino acid sequence. These repeats are characterized by a high proportion of charged amino acids. Secondary structure analyses predict that the majority of the encoded protein could form alpha-helical structures that might form filamentous aggregates of intermediate filament dimensions, even though the heptad motif obligatory for the intermediate filament structure itself is absent. The alternative structural role of trichohyalin could be as an intermediate filament-associated protein, as proposed from other evidence.

scholarly journals Stereoselective Access to Azetidine-Based α-Aminoacids and Applications to Small Peptides Synthesis

2020 ◽  
Author(s):  
Felix Reiners ◽  
Emanuel Joseph ◽  
Benedikt Nißl ◽  
Dorian Didier
Keyword(s):  
Amino Acids ◽  
Recent Progress ◽  
Asymmetric Reduction ◽  
Building Blocks ◽  
Membered Ring ◽  
Small Peptides ◽  
Small Peptide ◽  
Unsaturated Carboxylic Acids ◽  
Peptides Synthesis ◽  
Metal Catalyzed

Recent progress on four-membered ring building blocks has led us to investigate the formation of non-natural azetidine-based amino acids (<i>Aze</i>). A simple organometallic route was developed to access unsaturated carboxylic acids, which were further engaged in metal catalyzed asymmetric reduction. Functionalized <i>Aze</i> derivatives were finally employed in the formation of small peptide chains.

A bis-copper(II)–[D-βVal3,7]ascidiacyclamide complex enveloping two square pyramids and sharing an apex atom from a carbonate anion

2019 ◽  
Vol 75 (8) ◽  
pp. 1182-1187 ◽  
Author(s):  
Akiko Asano ◽  
Mitsinobu Doi
Keyword(s):  
Amino Acids ◽  
Water Molecule ◽  
Copper Complex ◽  
Structural Changes ◽  
Ring Expansion ◽  
Membered Ring ◽  
Water Molecules ◽  
Ring Size ◽  
Cd Spectra ◽  
Carbonate Anion

The four azole rings place structural restrictions on ascidiacyclamide (ASC). As a result, the structure of ASC exists in an equilibrium between two major forms (i.e. folded and square). [D-βVal3,7]Ascidiacyclamide (βASC) was synthesized by replacing two D-Val-Thz (Val is valine and Thz is thiazole) blocks with D-β-Valine (D-βVal-Thz). This modification expands the peptide ring; the original 24-membered macrocycle of ASC becomes a 26-membered ring. Circular dichroism (CD) spectra showed that, in solution, the structural equilibrium is maintained with βASC, but the folded form is dominant. A copper complex was prepared, namely [[D-βVal3,7]ascidiacyclamide(2−)]aqua-μ-carbonato-dicopper(II) monohydrate, [Cu2(C38H54N8O6S2)(CO3)(H2O)]·H2O, to determine the effect of the change in ring size on the coordinated structure. The obtained bis-CuII–βASC complex contains two water molecules and a carbonate anion. Two CuII ions are chelated by three N-donor atoms of two Thz–Ile–Oxz (Ile is isoleucine and Oxz is oxazoline) units. An O atom of the carbonate anion bridges two CuII ions, forming two square pyramids. These features are similar to the previously reported structure of the CuII–ASC complex, but the two pyramids are enveloped inside the peptide and share one apex. In the CuII–ASC complex, the apex of each square pyramid is an O atom of a water molecule, and the two pyramids are oriented toward the outside of the peptide. The incorporated β-amino acids of βASC make the space inside the peptide large enough to envelop the two square pyramids. The observed structural changes in the bis-CuII–βASC complex arising from ring expansion are particularly interesting in the context of the previously reported structure of the CuII–ASC complex.

Tropolone-Based Treatments for Visualising Latent Fingermarks on Porous Surfaces

2019 ◽  
Author(s):  
Clara M. Agapie ◽  
Melissa Sampson ◽  
William Gee
Keyword(s):  
Amino Acids ◽  
Uv Radiation ◽  
Membered Ring ◽  
Diazonium Salts ◽  
Chemical Detection ◽  
Latent Fingerprints ◽  
Porous Surfaces

The work describes a new chemical means of visualising latent fingerprints (fingermarks) using tropolone. Tropolone reacts with amino acids within the fingermark residue to form adducts that absorb UV radiation. These adducts provide useful contrast on highly-fluorescent prous surfaces will illuminated with UV radiation. The conjugated seven-membered ring of the tropolone adduct can be reacted further diazonium salts, which is demonstrated here with formation of two dyes. The methodology is extremely rapid, occurring in minutes with mild heating, and can be applied before ninhydrin in a chemical detection sequence. <br>

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