scholarly journals Studies on Chitin II. Reaction of N-Acetyl-D-Glucosamine With a-Amino Acids, Peptides, and Proteins

1955 ◽  
Vol 8 (1) ◽  
pp. 83 ◽  
Author(s):  
RH Hackman
Keyword(s):  
Amino Acids ◽  
Ethyl Ester ◽  
Equilibrium Dialysis ◽  
Equilibrium Constants ◽  
Amino Nitrogen ◽  
Cuticular Proteins ◽  
Alkaline Conditions ◽  
Acidic Conditions ◽  
Glycine Ethyl Ester ◽  
Ph Range

The reaction of N-acetyl-D-glucosamine with a-amino acids, peptides, and proteins has been investigated. The course of the reaction has been followed by methods which involved the use of paper partition chromatography, polarimetric measurements, measurement of pH depression, and equilibrium dialysis. It is considered that products of the Schiff base (or azomethine) type are formed but the combination is unstable and is split even in the biological pH range. No reaction occurs under acidic conditions but ~der alkaline conditions the amount of reaction increases with the pH. At a given pH the percentage combination depends upon the equilibrium constant of the reaction and upon the dissociation constant of the a-amino nitrogen, as this determines the initial concentration of the reagent. Differences in the degrees of ionization are more important in determining the percentage combination than are the differences in the equilibrium constants. The reaction is of a similar type to that which occurs between glucose and a-amino acids or peptides. Tyrosine, as well as free a-amino groups, appears to play an important part in the binding of N-acetyl-D-glucosamine by insect cuticular proteins. 2-Acetamido-2-deoxyN'- D-glucosylglycine ethyl ester has been synthesized from N-acetyl-D-glucosamine and glycine ethyl ester and its properties have been investigatd.

scholarly journals UVA and UVB Photoprotective Capabilities of Topical Formulations Containing Mycosporine-like Amino Acids (MAAs) through Different Biological Effective Protection Factors (BEPFs)

Marine Drugs ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 55 ◽  
Author(s):  
Francisca de la Coba ◽  
José Aguilera ◽  
Nathalie Korbee ◽  
María de Gálvez ◽  
Enrique Herrera-Ceballos ◽  
...  
Keyword(s):  
Amino Acids ◽  
In Vitro Tests ◽  
Antioxidant Compounds ◽  
Protection Factor ◽  
Effective Protection ◽  
Alkaline Conditions ◽  
Solar Uv ◽  
The Stability ◽  
Ph Range

The safety and stability of synthetic UV-filters and the procedures for evaluating the photoprotective capability of commercial sunscreens are under continuous review. The influence of pH and temperature stressors on the stability of certain Mycosporine-like amino acids (MAAs) isolated at high purity levels was examined. MAAs were highly stable at room temperature during 24 h at pH 4.5–8.5. At 50 °C, MAAs showed instability at pH 10.5 while at 85 °C, progressive disappearances were observed for MAAs through the studied pH range. In alkaline conditions, their degradation was much faster. Mycosporine-serinol and porphyra-334 (+shinorine) were the most stable MAAs under the conditions tested. They were included in four cosmetically stable topical sunscreens, of which the Sun Protection Factor (SPF) and other Biological Effective Protection Factors (BEPFs) were calculated. The formulation containing these MAAs showed similar SPF and UVB-BEPFs values as those of the reference sunscreen, composed of synthetic UV absorbing filters in similar percentages, while UVA-BEPFs values were slightly lower. Current in vitro data strongly suggest that MAAs, as natural and safe UV-absorbing and antioxidant compounds, have high potential for protection against the diverse harmful effects of solar UV radiation. In addition, novel complementary in vitro tests for evaluation of commercial sunscreens efficacy are proposed.

Synthesis of amino acids. Alkylation of aldimine and ketimine derivatives of glycine ethyl ester under various phase-transfer conditions

1982 ◽  
Vol 23 (41) ◽  
pp. 4255-4258 ◽  
Author(s):  
Léon Ghosez ◽  
Jean-Pierre Antoine ◽  
Etienne Deffense ◽  
Mirtha Navarro ◽  
Valery Libert ◽  
...  
Keyword(s):  
Amino Acids ◽  
Ethyl Ester ◽  
Phase Transfer ◽  
Glycine Ethyl Ester ◽  
Derivatives Of

Evaluation of inorganic adsorbents for the removal of problematic textile dyes and pesticides

1997 ◽  
Vol 36 (2-3) ◽  
pp. 173-180 ◽  
Author(s):  
S. D. Lambert ◽  
N. J. D. Graham ◽  
C. J. Sollars ◽  
G. D. Fowler
Keyword(s):  
Activated Carbon ◽  
Textile Industry ◽  
Reactive Dyes ◽  
Textile Dyes ◽  
Temperature Range ◽  
Alkaline Conditions ◽  
Acidic Conditions ◽  
Ph Range ◽  
Inorganic Adsorbents ◽  
Synthetic Clay

This paper evaluates three inorganic adsorbents (activated bauxite, fullers earth and a synthetic clay), relative to activated carbon, for the removal of several representative contaminants of major concern and frequent occurrence in UK textile industry effluents; reactive dyes, pentachlorophenol and Propetamphos. The results indicate that, for the removal of reactive dyes, the synthetic clay was the most effective adsorbent over the pH range from pH 5.5 to pH 8.5 and temperature range from 20 to 40°C, although comparable dye removals were exhibited by activated carbon under neutral and alkaline conditions. Under acidic conditions activated bauxite was as effective as activated carbon. Fullers Earth was largely ineffective. With regard to the removal of pesticides activated carbon was highly effective, whereas the three inorganic adsorbents showed negligible removals.

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