3415-08-5Relevant articles and documents
Separated coil and chain aggregation behaviors on the miscibility and helical peptide secondary structure of poly(tyrosine) with poly(4-vinylpyridine)
Lu, Yi-Syuan,Lin, Yung-Chih,Kuo, Shiao-Wei
, p. 6547 - 6556 (2012)
In this study, we synthesized a low-molecular-weight polytyrosine (PTyr) through living ring-opening polymerization of the α-amino acid-N-carboxyanhydride and then blended it with poly(4-vinylpyridine) (P4VP) homopolymer in N,N-dimethylformamide (DMF) and MeOH solutions, thereby controlling the miscibility behavior and secondary structures of the PTyr. Infrared spectroscopy revealed that the PTyr/P4VP mixture featured strong hydrogen bonds between the OH groups of PTyr and the pyridyl groups of P4VP. Differential scanning calorimetry revealed that the glass transition temperatures of the PTyr/P4VP complexes formed from MeOH solutions were higher than those of the corresponding PTyr/P4VP miscible blends obtained from DMF solutions. The behavior of the PTyr/P4VP blends obtained after evaporation of the DMF solutions was consistent with separated random coils of the PTyr chains. The increased degree of hydrogen bonding within the PTyr/P4VP complexes formed from MeOH solutions resulted in interpolymer complex aggregates; the corresponding enhanced intermolecular hydrogen bonding of PTyr with P4VP resulted in β-sheet conformations for PTyr, as evidenced from Fourier transform infrared spectroscopy, solid state nuclear magnetic resonance spectroscopy, and wide-angle X-ray diffraction analyses. This model, which takes advantage of the well-defined secondary structures (α-helices, β-sheets) of PTyr, can, therefore, be used to identity the behavior of separated coils and aggregated chains in polymer blend and complex systems.
METHOD FOR PRODUCING AMINO ACID-N-CARBOXYLIC ACID ANHYDRIDE
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Paragraph 0083, (2020/08/07)
PROBLEM TO BE SOLVED: To provide: a method for safely and efficiently producing amino acid-N-carboxylic acid anhydride; and a method for producing peptide by using the obtained amino acid-N-carboxylic acid anhydride. SOLUTION: The method for producing an amino acid-N-carboxylic acid anhydride according to the present invention is characterized in that the amino acid-N-carboxylic acid anhydride is represented by the following formula (II), and a step of irradiating a composition containing a halogenated methane and an amino acid compound represented by the following formula (I) with high energy light in the presence of oxygen is included. [In the formula, R1 represents an amino acid side chain group in which the reactive group is protected, and R2 represents H or the like.]. SELECTED DRAWING: None COPYRIGHT: (C)2020,JPOandINPIT
METHOD FOR PREPARATION OF N-CARBOXYANHYDRIDES
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Page/Page column 11, (2020/05/12)
The invention discloses a method for the preparation off N-carboxyanhydrides (NCAs) by reaction of amino acids with phosgene.(II)
Enzyme responsive supramolecular hydrogels assembled from nonionic peptide amphiphiles
Liu, Rui,Shi, Zhekun,Sun, Jing,Li, Zhibo
, p. 1314 - 1319 (2018/08/17)
Smart peptide hydrogels are of great interest for their great potential applications. Here, we report a facile approach to prepare a class of enzyme-responsive hydrogels in a scalable manner. These hydrogels self-assemble from a family of nonionic peptide amphiphiles (PAs) synthesized by sequential ring-opening polymerization (ROP) of γ-benzyl-L-glutamate N-carboxyanhydride (BLG-NCA) and L-tyrosine N-carboxyanhydride (Tyr-NCA), followed by subsequent aminolysis. These PA samples can readily form a clear hydrogel with a critical gelation concentration as low as 0.5 wt%. The incorporation of tyrosine residues offers hydrophobicity, hydrogen-bonding interaction and enzyme-responsive properties. The hydrogel-to-nanogel transition is observed under physiological conditions in the presence of horseradish peroxidase (HRP) and hydrogen peroxide (H2O2). The obtained PA hydrogels are ideal candidates for the new generation of smart scaffolds.
Hydrogen bonding interactions affect the hierarchical self-assembly and secondary structures of comb-like polypeptide supramolecular complexes displaying photoresponsive behavior
Mohamed, Mohamed Gamal,Tu, Jia-Huei,Huang, Shih-Hung,Chiang, Yeo-Wan,Kuo, Shiao-Wei
, p. 51456 - 51469 (2016/06/09)
In this study we blended 4-(4-hexadecylphenylazo)pyridine (AzoPy-C16), synthesized through facile diazonium and monoetherification reactions, with polytyrosine (PTyr) to form comb-like polypeptide supramolecular complexes stabilized through hydrogen bonding between the pyridyl ring of each AzoPy-C16 unit and the OH groups of PTyr. The secondary structure of PTyr transformed from an α-helical to a β-sheet conformation upon the addition of AzoPy-C16, because the long alkyl chains of the AzoPy-C16 units disrupted the weak intramolecular hydrogen bonds between the CO and NH groups in the α-helical conformation, as determined using Fourier transform infrared (FTIR) and circular dichroism (CD) spectroscopy. Small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) suggested a hierarchical lamellae-within-lamellae structure for the PTyr/AzoPy-C16 supramolecular complex, featuring long-range-ordered lamellae arising from the antiparallel β-pleated sheet conformation of PTyr (d = 1.15 nm) within long-range-ordered lamellae arising from the alkyl groups of AzoPy-C16 units (d = 5.94 nm), oriented in a perpendicular manner. The d-spacing and long-range order of the lamellar structure formed from the alkyl groups decreased upon UV irradiation as the rod-like trans isomers of the AzoPy-C16 units transformed into V-shaped cis counterparts. This phenomenon also led to a change in the water contact angle of the supramolecular material, with the hydrophobic surface of PTyr/trans-AzoPy-C16 (94.2°) transforming to a hydrophilic surface for PTyr/cis-AzoPy-C16 (61.3°).
Combined atom-transfer radical polymerization and ring-opening polymerization to design polymer-polypeptide copolymer conjugates toward self-aggregated hybrid micro/nanospheres for dye encapsulation
Saha, Anupam,Paira, Tapas K.,Biswas, Mrinmoy,Jana, Somdeb,Banerjee, Sanjib,Mandal, Tarun K.
, p. 2313 - 2319 (2015/09/15)
A designed orthogonal dual initiator is employed to construct poly(methyl methacrylate)-block-polytyrosine copolymer conjugates via the combination of atom-transfer radical polymerization of methyl methacrylate, "click" chemistry and ring-opening polymerization of tyrosine-α-amino acid N-carboxyanhydride monomer. The polymer-polypeptide conjugate undergoes self-aggregation in dimethylformamide to produce hybrid micro/nanospheres owing to the formation of composite micelle as evidenced from field emission scanning electron microscopy and dynamic light scattering study. A simple solution-based approach is described to encapsulate an organic dye (Rhodamine-6G) into the aggregated hybrid micro/nanospheres.
Investigation of N-carbamoylamino acid nitrosation by {NO + O2 in the solid-gas phase. Effects of NOx speciation and kinetic evidence for a multiple-stage process
Lagrille, Olivier,Taillades, Jacques,Boiteau, Laurent,Commeyras, Auguste
, p. 271 - 284 (2008/03/14)
Nitrosation of N-carbamoylamino acids (CAA) by gaseous NO + O2, an interesting synthetic pathway to amino acid N-carboxyanhydrides (NCA), alternative to the phosgene route, was investigated on N-carbamoyl-valine either in acetonitrile suspension or solventless conditions, and compared to the classical nitrosating system NaNO2 + CF3COOH (TFA), the latter being quite less efficient in terms of either rate, stoichiometric demand, or further tractability of the product. The rate and efficiency of the NO + O2 reaction mainly depends on the O2/NO ratio. Evaluation of the contribution of various nitrosating species (N 2O3, N2O4, HNO2) through stoichiometric balance showed the reaction to be effected mostly by N 2O3 for O2/NO ratios below 0.3, and by N 2O4 for O2/NO ratios above 0.4. The relative contribution of (subsequently formed) HNO2 always remains minor. Differential scanning calorimetry (DSC) monitoring of the reaction in the solid phase by either HNO2 (from NaNO2 + TFA), gaseous N 2O4 or gaseous N2O3, provides the associated rate constants (ca. 0.1, 2 and 108 s-1 at 25°C, respectively), showing that N2O3 is by far the most reactive of these nitrosating species. From the DSC measurement, the latent heat of fusion of N2O3, 2.74 kJ ·mol-1 at -105 °C is also obtained for the first time. The kinetics was investigated under solventless conditions at 0°C, by either quenching experiments or less tedious, rough calorimetric techniques. Auto-accelerated, parabolic-shaped kinetics was observed in the first half of the reaction course, together with substantial heat release (temperature increase of ca. 20°C within 1-2 min in a 20-mg sample), followed by pseudo-zero-order kinetics after a sudden, important decrease in apparent rate. This kinetic break is possibly due to the transition between the initial solid-gas system and a solid-liquid-gas system resulting from water formation. Overall rate constants increased with parameters such as the specific surface of the solid, the O 2/NO ratio, or the presence of moisture (or equivalently the hydrophilicity of the involved CAA), however without precise relationship, while the last two parameters may directly correlate to the increasing acidity of the medium. Copyright
