scholarly journals Heterogeneous distribution of amino groups in partially N-acetylated derivatives of chitosan.

1981 ◽  
Vol 45 (6) ◽  
pp. 1335-1339 ◽  
Author(s):  
Shigehiro HIRANO ◽  
Shigeru TSUNEYASU ◽  
Yotaro KONDO
Keyword(s):  
Amino Groups ◽  
Heterogeneous Distribution ◽  
Derivatives Of

Heterogeneous Distribution of Amino Groups in PartiallyN-Acetylated Derivatives of Chitosan

1981 ◽  
Vol 45 (6) ◽  
pp. 1335-1339
Author(s):  
Shigehiro Hirano ◽  
Shigeru Tsuneyasu ◽  
YÒTaro Kondo
Keyword(s):  
Amino Groups ◽  
Heterogeneous Distribution ◽  
Derivatives Of

scholarly journals Appendix: Synthesis of N-acylglutathione derivatives by dimethylaminopyridine catalysis

1982 ◽  
Vol 207 (2) ◽  
pp. 329-332 ◽  
Author(s):  
Claudius D'Silva ◽  
Amina Al-Timari ◽  
Kenneth T. Douglas
Keyword(s):  
General Procedure ◽  
Amino Groups ◽  
Derivatives Of

A general procedure, involving 4-dimethylaminopyridine-catalysed acylation of the amino groups in the appropriate S-blocked glutathione, is reported for the preparation of N-blocked derivatives of glutathiones.

scholarly journals Isoelectric points of erabutoxins and monoacyl derivatives of erabutoxin b. Estimation of the pK values of amino groups in erabutoxins by using isoelectric-focusing data

1982 ◽  
Vol 203 (2) ◽  
pp. 427-433 ◽  
Author(s):  
N UI ◽  
C Takasaki ◽  
N Tamiya
Keyword(s):  
Isoelectric Focusing ◽  
Isoelectric Point ◽  
Amino Group ◽  
Amino Groups ◽  
Sea Snake ◽  
Isoelectric Points ◽  
Point Data ◽  
Laticauda Semifasciata ◽  
Erabutoxin B ◽  
Derivatives Of

The isoelectric points of erabutoxins a, b and c, neurotoxic proteins of a sea snake, Laticauda semifasciata, were determined by density-gradient isoelectric focusing. The same measurement was also made with monoacyl derivatives of erabutoxin b, in which each one of all amino groups had been either acetylated or propionylated. Erabutoxins a and b showed the same isoelectric point at pH 9.68. The values for [1-N alpha-acetyl-arginine]-, [15-N6-acetyl-lysine]-, [27-N6-acetyl-lysine]-, [47-N6-propionyl-lysine]- and [51-N6-acetyl-lysine]-erabutoxin b were at pH 9.52, 9.31, 9.45, 9.22 and 9.09 respectively, being definitely different from each other and lower than the value for the unmodified molecule. The isoelectric point of erabutoxin c, which is [51-asparagine]-erabutoxin b, was the same as that of [51-N6-acetyl-lysine]erabutoxin b. Assuming that no change in pK occurs on monoacylation, the pK values of amino groups in erabutoxin b were calculated from the isoelectric-point data. It is indicated that the pK values of zeta-amino groups differ markedly from each other and that the value of alpha-amino group is anomalously high.

Synthesis of 2-Deoxy-β-D-ribonucleosides and 2,3-Dideoxy-β-D-pentofuranosides on Immobilized Bacterial Cells

1994 ◽  
Vol 59 (10) ◽  
pp. 2303-2330 ◽  
Author(s):  
Ivan Votruba ◽  
Antonín Holý ◽  
Hana Dvořáková ◽  
Jaroslav Günter ◽  
Dana Hocková ◽  
...  
Keyword(s):  
The Other ◽  
Bacterial Cells ◽  
Amino Groups ◽  
E Coli ◽  
Pyrimidine Series ◽  
Acceptor Activity ◽  
Dependent Strain ◽  
Pyrimidine Bases ◽  
Heterocyclic Bases ◽  
Derivatives Of

Alginate gel-entrapped cells of auxotrophic thymine-dependent strain of E. coli catalyze the transfer of 2-deoxy-D-ribofuranosyl moiety of 2'-deoxyuridine to purine and pyrimidine bases as well as their aza and deaza analogs. All experiments invariably gave β-anomers; in most cases, the reaction was regiospecific, affording N9-isomers in the purine and N1-isomers in the pyrimidine series. Also a 2,3-dideoxynucleoside can serve as donor of the glycosyl moiety. The acceptor activity of purine bases depends only little on substitution, the only condition being the presence of N7-nitrogen atom. On the other hand, in the pyrimidine series the activity is limited to only a narrow choice of mostly short 5-alkyl and 5-halogeno uracil derivatives. Heterocyclic bases containing amino groups are deaminated; this can be avoided by conversion of the base to the corresponding N-dimethylaminomethylene derivative which is then ammonolyzed. The method was verified by isolation of 9-(2-deoxy-β-D-ribofuranosyl) derivatives of adenine, guanine, 2-chloroadenine, 6-methylpurine, 8-azaadenine, 8-azaguanine, 1-deazaadenine, 3-deazaadenine, 1-(2-deoxy-β-D-ribofuranosyl) derivatives of 5-ethyluracil, 5-fluorouracil, and 9-(2,3-dideoxy-β-D-pentofuranosyl)hypoxanthine, 9-(2,3-dideoxy-β-D-pentofuranosyl)-6-methylpurine, and other nucleosides.

Syntheses of Enantiomeric N-(3-Hydroxy-2-phosphonomethoxypropyl) Derivatives of Purine and Pyrimidine Bases

1993 ◽  
Vol 58 (3) ◽  
pp. 649-674 ◽  
Author(s):  
Antonín Holý
Keyword(s):  
Benzoyl Chloride ◽  
Sodium Hydride ◽  
Cesium Carbonate ◽  
Amino Groups ◽  
Heterocyclic Base ◽  
Pyrimidine Bases ◽  
Derivatives Of ◽  
General Method

Methods of preparation of N-(3-hydroxy-2-phosphonomethoxypropyl) (HPMP) derivatives of (2S)- and (2R)-configuration (compounds I and XXVII, respectively) are described. The general method starts from the corresponding N-(2,3-dihydroxypropyl) derivatives which were converted either into the (R)-enantiomers XIII by reaction of the base with (R)-glycidol butyrate (XII) in the presence of cesium carbonate and subsequent methanolysis, or into the (S)-enantiomers XI by alkylation of the base with (R)-2,2-dimethyl-4-tosyloxymethyl-1,3-dioxolane (V) in the presence of the same reagent. The amino groups on the heterocyclic base in compounds XI and XIII were benzoylated by silylation followed by reaction with benzoyl chloride and the obtained N-benzoates XV and XVII on reaction with trityl chloride afforded the corresponding 3'-O-trityl derivatives XVI and XVIII. These compounds were condensed with bis(2-propyl) p-sulfonyloxymethylphosphonate (XXIII) in dimethylformamide in the presence of sodium hydride to give the fully protected diesters XXIV and XXVIII. These compounds could be selectively acid-hydrolyzed to remove the trityl group only under formation of compounds XXXV, or methanolyzed and then acid-hydrolyzed to remove the trityl and N-benzoyl groups and lead to compounds XXVI and XXX, or treated with bromotrimethylsilane to remove the trityl and 2-propyl group to give phosphonates of the type XXXI. All the three types of compounds were then converted into free phosphonates of the (S)-series (I) and the (R)-series (XXVII). Derivatives of cytosine (Ia, XXVIIa), adenine (Ib, XXVIIb), 2,6-diaminopurine (Ic, XXVIIc) and guanine (Id, XXVIId) were prepared. Condensation of the partially blocked adenine deriavtive XXXV with the tosyl derivative XXIII and subsequent deprotection afforded 9-(S)-(2,3-diphosphonomethoxy propyl)adenine (XLIII). Reaction of the same compound XXXV or its (R)-enantiomer XXXVIII with diethyl phosphonate , followed by deblocking, afforded 3'-O-phosphoryl derivatives (S)-HPMPA (XXXVII) and (R)-HPMPA (XL).

scholarly journals New N-difluoromethylindoles: features of N-difluoromethylation of indoles with electron-donor or electron-withdrawing substituents

2018 ◽  
Vol 6 (1) ◽  
pp. 101-108
Author(s):  
Kirill Petko ◽  
Andrey Filatov
Keyword(s):  
Electron Donor ◽  
Bromine Atom ◽  
Indole Derivatives ◽  
Amino Groups ◽  
Derivatives Of ◽  
Electron Withdrawing Substituents

The study of the difluoromethylation of various indole derivatives containing both electron-donating and electron-withdrawing groups was carried out. N-Difluoromethyl derivatives of indole with methoxy, methyl, nitro, cyano, amino groups and bromine atom were isolated and fully characterized.

scholarly journals Synthesis of O-tyrosine Phosphorylated Adducts of Methylphosphonic and Phosphoric Acid Derivatives as Reference Compounds for the Analysis of Biomedical Samples

2019 ◽  
Vol 3 (2) ◽  
pp. 103-110
Author(s):  
Krylov V.I. Rybalchenko I.V.
Keyword(s):  
Atmospheric Pressure ◽  
The Body ◽  
Chemical Weapons ◽  
Amino Groups ◽  
Chemical Agents ◽  
Chemical Weapons Convention ◽  
Toxic Agents ◽  
Protective Groups ◽  
Derivatives Of ◽  
Reference Samples

Organophosphorus chemical agents are included in the 1st List of the Annex on Chemicals of the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction (Chemical Weapons Convention, CWC). For the purposes of verification of compliance with the provisions of the CWC, special methods, which are considered the most informative at determining the retrospective effects of organophosphorus toxicants on the body, are necessary. Typical long-lived biomarkers of organophosphate toxic agents are tyrosine phosphorylation products, the presence of which in biomedical samples clearly indicates the exposure to sarin, soman, tabun and V-series agents. We have elaborated methods for the synthesis and isolation of tyrosine adducts derivatives of methylphosphonic and phosphoric acids, used as reference samples. The synthesis scheme included the consecutive protection of carboxyl and amino groups of tyrosine, its O-phosphorylation by the corresponding alkylphosphonates and phosphates, the removal of protective groups with the release of corresponding O-phosphorylated tyrosine adducts. Their purification from im purities was carried out, using column chromatography (SiO2, eluent: dichloromethane/ethyl acetate 1:1). The purity of the obtained products was more than 90 %, so it was possible to involve them in further transformations with the use of catalyst without the threat of its «poisoning». Benzyl and carboxybenzyl protection of phosphorylated L-tyrosines (12–17) was removed by means of catalytic hydrogenation by molecular hydrogen under atmospheric pressure. Target adducts of phosphorylated reagents and L-tyrosin were obtained (63–82 %) in form of crystal white substances, readily soluble in water and ethanol, and poorly – in dichloromethane and acetonitrile

Sorption of Substituted Phenylamides onto Bovine Serum Albumin

Weed Science ◽  
1971 ◽  
Vol 19 (3) ◽  
pp. 269-273 ◽  
Author(s):  
N. D. Camper ◽  
D. E. Moreland
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Phenyl Ring ◽  
Protein Modification ◽  
Carbonyl Oxygen ◽  
Amide Hydrogen ◽  
Amino Groups ◽  
Influence Of Ph ◽  
Derivatives Of

The influence of pH, temperature, ionic strength, and protein modification on the sorption (moles of chemical bound per mole of protein) of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron) and 3′,4′-dichloropropionanilide (propanil) to bovine serum albumin (hereinafter referred to as BSA) was examined. Free amino groups of BSA were involved in the binding of both diuron and propanil. In addition, tryptophanyl residues appeared to be involved in the binding of propanil. Studies made with derivatives of diuron suggested that the amide hydrogen and carbonyl oxygen of the phenylamide are involved in the binding mechanism. Conformation of the protein was suggested to control the extent of binding. Increased chlorination of the phenyl ring was correlated with increased binding onto BSA. Propanil was bound to a greater extent than diuron by the protein.

scholarly journals Well-Defined Construction of Functional Macromolecular Architectures Based on Polymerization of Amino Acid Urethanes

Biomedicines ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 317
Author(s):  
Takeshi Endo ◽  
Atsushi Sudo
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Primary Amines ◽  
Amino Groups ◽  
Molecular Weights ◽  
Antifouling Coatings ◽  
Onium Salts ◽  
Polypeptide Synthesis ◽  
Produce Amino Acid ◽  
Derivatives Of

Polypeptide synthesis was accomplished using the urethane derivatives of amino acids as monomers, which can be easily prepared, purified, and stored at ambient temperature without the requirement for special precautions. The urethanes of amino acids are readily synthesized by the N-carbamoylation of onium salts of amino acids using diphenyl carbonate (DPC). The prepared urethanes are then efficiently cyclized to produce amino acid N-carboxyanhydrides (NCAs). Thereafter, in the presence of primary amines, the ring-opening polymerization (ROP) of NCAs is initiated using the amines, to yield polypeptides with controlled molecular weights. The polypeptides have propagating chains bearing reactive amino groups and initiating chain ends endowed with functional moieties that originate from the amines. Aiming to benefit from these interesting characteristics of the polypeptide synthesis using the urethanes of amino acids, various macromolecular architectures containing polypeptide components have been constructed and applied as biofunctional materials in highly efficient antifouling coatings against proteins and cells, as biosensors for specific molecules, and in targeted drug delivery.

Infrared spectra of 2,4-dinitro and 2,6-dinitroaniline derivatives

1982 ◽  
Vol 47 (4) ◽  
pp. 1100-1111 ◽  
Author(s):  
Jaroslav Majer ◽  
Vladimír Kadeřábek
Keyword(s):  
Absorption Spectra ◽  
Infrared Spectra ◽  
Infrared Absorption ◽  
Point Of View ◽  
Amino Groups ◽  
Infrared Absorption Spectra ◽  
Derivatives Of

Infrared absorption spectra of N-substituted derivatives of 2,4-dinitro- and 2,6-dinitroanilines have been measured and interpreted from the point of view of bond and sterical interactions of the substituted amino groups with the both nitro groups.

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