The cross-linking of gelatin using a water-solublecarbodiimide.

Due to the vast importance of peptides in biological processes, there is an escalating need for synthetic peptides to be used in a wide variety of applications. However, the consumption of organic solvent is extremely large in chemical peptide syntheses because of the multiple condensation steps in organic solvents. That is, the current synthesis method is not environmentally friendly. From the viewpoint of green sustainable chemistry, we focused on developing an organic solvent-free synthetic method using water, an environmentally friendly solvent. Here we described in-water synthesis technology using water-dispersible protected amino acids.

A convenient synthesisof water-soluble carbodiimides.

Notes- A Convenient Synthesis of Water-Soluble Carbodiimides

Notes- A Convenient Synthesis of Water-Soluble ..

One of the important factors for good solid-phase reactivity in water is the homogeneous mixing of the nanoparticulate amino acids and a resin. Since active surfactants are known as excellent dispersible agents, nanosuspensions of protected amino acids dispersed with active surfactants would lead to further good reactivity even in water. Triton X-100 is known to inhibit aggregation of the peptide chain. We examined preparation of dispersible Fmoc-amino acid nanoparticles in water containing Triton X-100 as a dispersion agent. The sizes of the resulting water-dispersible nanoparticles were summarized in Table . The best condition is entry 2 in which nanoparticles were prepared in aqueous 0.2% Triton X-100 solution using 0.5 mm zirconium oxide beads. The minimum average particle size observed was 217 nm. It was not possible to reduce the sizes of all particles to 100 nm or less. Next we synthesized Leu-enkephalinamide by in-water solid-phase method described in Table using dispersible Fmoc-amino acid nanoparticles in water containing Triton X-100 []. HPLC analysis showed a single major peak corresponding to Leu-enkephalinamide, and the total yield was 79%. The purities of crude peptides cleaved from the resin were over 90% and similar to the results by the general Fmoc synthesis method using organic solvents.

Notes- A Convenient Synthesis of Water-Soluble Carbodiimides.

Amphotericin B (AmB), a well-known polyene antifungal agent displays a marked tendency to self-associate and, as a consequence, exhibits very poor solubility in water. The therapeutic index of AmB is low, and is associated with significant dose-related nephrotoxicity, as well as acute, infusion-related febrile reactions. Reports in the literature indicate that that toxicity of AmB may be related to the physical state of the drug. Reaction of AmB in dimethylformamide with bis(dimethylaminopropyl)carbodiimide yielded an unexpected N-alkylguanidine/N-acylurea bis-adduct of AmB which was highly water soluble. The absorption spectrum of the AmB derivative in water indicated excellent monomerization, and the anti-fungal activities of reference AmB and its water-soluble derivative against C. albicans were found to be virtually identical. Furthermore, the water-soluble adduct is significantly less active in engaging TLR4 which would suggest that the adduct may be less proinflammatory.

(1961) A Convenient Synthesis of Water-Soluble Carbodiimides, ..

The solid-phase concept, in which the reaction is carried out on a solid support, was originally developed by Merrifield []. Solid-phase synthesis typically offers many advantages over the conventional synthesis in terms of efficiency as well as due to the convenient applicability and purification procedures. Since solid-phase synthesis is performed in a two-phase (liquid and solid phases) medium, for efficient solid-phase reaction, it is necessary that therefore the building blocks and reagents generally have good solubility in solvents. Currently, solid-phase peptide synthesis is performed by the Fmoc strategy in most cases. Fmoc-protected amino acids, however, are poorly soluble in water and therefore not adequate for use in the solid-phase synthesis in water. Recently with the aim of achieving solid-phase peptide synthesis in water, we developed in-water solid phase synthesis using water-dispersible nanoparticulate Fmoc-amino acids (Figure ) [,].

Convenient synthesis of water-soluble ..

Industrial synthesis of peptides on the market, including pharmaceutical products, is generally performed in organic solvents by the solution-phase. Boc-amino acid is widely used in the industrial chemistry and well-known to be suitable for green chemistry because only gases were generated in the removal step of Boc group. Although Boc-amino acids are highly soluble in organic solvent, these are sparingly soluble in water. Therefore, we also developed a method to synthesize peptides in water by the solution-phase using water-dispersible Boc-amino acid nanoparticles []. When Boc-amino acids are converted to nanoparticles homogenously dispersed in water, the specific surface area is increased and water dissolution speed is improved. We hypothesized that the reaction can be dramatically accelated, even when water-insoluble Boc amino acids are used (Figure ).

of water-soluble and basic carbodiimides in ..

Chemical peptide synthesis is classified into two types: solid-phase synthesis and solution-phase synthesis. Choosing the best amino acid derivatives is one of the most important, and sometimes difficult, aspects of peptide synthesis. Currently, Fmoc-amino acids are routinely used building blocks for solid-phase peptide synthesis [,]. In solution-phase synthesis, tert-butyloxycarbonyl (Boc)-protected amino acids are commonly used. Both Fmoc- and Boc-amino acids are highly soluble in ordinary organic solvents. These molecules are sparingly soluble in water and are considered inappropriate for in-water peptide synthesis. We have developed technology using these common water-insoluble protected amino acids processed into water-dispersible nanoparticles to allow synthesis in water, and have reported that the use of water-dispersible nanoparticles is effective in dramatically reducing reaction time in water [-]. This review describes a method for solid-phase and solution-phase peptide synthesis in-water using water-dispersible protected amino acid nanoparticles.