Aspartame precursor

The aspartame precursor precipitates during the reaction, which pulls the reaction equilibrium to completion. 

Product Fructose syrup 7 - Decalactone 6-APA Aspartame precursor Cefuroxime... 

Table 12.2 reports, as an example, a comparison of different methods for ther-molysin-catalyzed synthesis of the aspartame precursor Z-L-Asp-L-Phe-OMe in terms of reaction yield and initial rate. 

Chiral chromatography can also be used in order to obtain resolution of stereoisomers from aspartame, its precursors, and its degradation products. Lin et al. (84), using a Chiracel OD column and a mobile phase of 2-propanol -hexane (1 1, v/v), achieved complete separation of aspartame precursors, dd-, dl-, LL-, and LD-[(Z)-AspOS-Bzl)-Phe-OCH3], Motellier and Wainer (85) separated four stereoisomers of aspartame, two of diketopiperazine, and three of aspartyl-phenylalanine using a stationary phase composed of a chiral crown either coated on a polymeric support—CrownPack CR( + )—a mobile phase of aqueous perchloric acid, pH 2.8, and modified... 

K. Kihara, andT. Hashimoto, Synthesis of an aspartame precursor by immobilized thermolysin in an organic solvent,... 

Kamihira et al. (1987) Batch Synthesis of aspartame precursors through esterification Thermolysin... 

Kamat, S. Critchley, G. Beckman, E. J. Russell, A. J. Biocatalytic Synthesis of Acrylates in Organic Solvents and Supercritical Fluids HI. Does Carbon Dioxide Covalently Modify Enzymes Biotechnol. Bioeng. 1995, 46, 610-620. Kamihira, M. Taniguchi, M. Kobayashi, T. Synthesis of Aspartame Precursors by Enzymatic Reaction in Supercritical Carbon Dioxide. Agric. Biol. Chem. 1987, 51, 3427-3428. 

Peptide synthesis is an extremely important area of chemistry for the pharmaceutical industry, and like any specialized area of chemistry, has its own set of unique problems associated with it. Racemization and purification of final products are two of the most difficult problems in this area. The use of enzymes has been explored as a possible answer to these problems since 1938 [29]. However, proteases needed to catalyze peptide synthesis are subject to rapid autolysis under the conditions needed to affect peptide coupling, so this has generally not been a practical approach until cross-linked enzyme crystals of proteases became available. The synthetic utility of protease-CLCs was demonstrated by the thermolysin CLC (PeptiCLEC -TR)-catalyzed preparation of the aspartame precursor Z-... 

The effect of DMSO on the initial reaction rate of a protease PST-01-catalyzed synthesis of Z-aspartame in a mixture of DMSO and Tris-HCl buffer at pH 8 was investigated by Tsuchiyama et al. [36], The initial reaction rate decreased with increasing DMSO concentration (20-70% (v/v)). At 50% (v/v) DMSO an 83% yield of aspartame precursor was obtained and at DMSO concentrations higher than 60% a precipitate assumed to be the protease was observed. 

Enantioselective Synthesis of an Aspartame Precursor with Thermolysin from Bacillus proteolicus (E.C. 3.4.24.27) I92 931... 

Enantioselective Synthesis of an Aspartame Precursor with Thermolysin... 

Murakami Y, Yoshida T, Hayashi S et al. (2000) Continuous enzymatic production of peptide precursor in aqueous/organic biphasic medium. Biotechnol Bioeng 69 57-65 Nakanishi K, Takeuchi A, Matsuno R (1990) Long term continuous synthesis of aspartame precursor in a column reactor with an immobilized thermolysin. Appl Microbiol Biot 32 633-636 Nardin EH, Calvo-CaUe JM, Oliveira GA et al. (1998). Plasmodium falciparum polyoximes highly immunogenic synthetic vaccines constructed by chemoselective ligation of repeat B-ceU epitopes and a universal T-ceU epitope of CS protein. Vaccine 16 590-600 Nilsson B, SoeUner M, Raines R (2005) Chemical synthesis of proteins. Annu Rev Biophys Biomol Struct 34 91-118... 

Y. Bono, K. Fukushima, G. Araya, H. Nabetani, and M. Nakajima, Performance of perstractive enzyme reactor for synthesis of aspartame precursor, J. Chem. Technol. Biotechnol. 70 (1997) 171-178. 

Enzymatic enantioselective reduction of 2-octanone Fungal decolourisation of a waste sludge Technetium Tc (VII) reduction with E. coli cells Enzymatic production of mannitol and gluconic acid Enzymatic production of L-glutamate Enzymatic production of oligodextrans Lipolysis of olive oil Cell-free protein synthesis Enzymatic synthesis of aspartame precursor Enzymatic resolution of amino acids... 

UF HF/dual recycle Enzymatic synthesis of aspartame precursor [156]... 

The effect of the wetting characteristics of the membrane in the hydrolytic activity of immobilized lipase was evaluated by Bouwer and co-workers [113]. These authors suggested that the larger thickness of the reaction layer in hydrophilic membranes, as compared to hydrophobic membranes, allowed the retention of the full enzyme activity. A lipase adsorbed onto polypropylene membranes in a hollow-fiber system was used for the selective hydrolysis of menhaden oil [112]. The experimental set-up led to the release of about 88% of the fatty acid residues and retention of more than 90% of the aimed eicosapen-taenoic and docosahexaenoic acids in a space-time of 3.5 h, while the half-life of the enzyme, under ideal operational conditions was 170 h. The enzymatic synthesis of an aspartame precursor in an organic-aqueous membrane-assisted two-liquid phase system has been continuously studied by Isono and co-workers [121, 149,156,201]. Productivity was increased from 6.6 to 8.4kgm d [121]. 

Polyethylene/filtration cell 30 - 40 nm Synthesis of aspartame precursor in aqueous-organic extractive system [121]... 

Tsuchiyama, S., Doukyu, N., Yasuda, M., Ishimi, K., Ogino, H. (2007). Peptide synthesis of aspartame precursor using organic-solvent-stable PST-01 protease in monophasic aqueous-organic solvent systems. Biotechnol. Progr., 23,820-823. 

Aspartame precursor synthesis in the presence of 30% DMSO and ethanol [38]... 

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