1991-78-2Relevant articles and documents
Engineered dehydrogenase biocatalysts for non-natural amino acids: Efficient isolation of the d-enantiomer from racemic mixtures
Paradisi, Francesca,Conway, Philip A.,Maguire, Anita R.,Engel, Paul C.
, p. 3611 - 3615 (2008)
With a view to their use in the kinetic resolution of racemic non-natural amino acids, five variants of the enzyme l-phenylalanine dehydrogenase, the wild-type enzyme from Bacillus sphaericus and four active-site mutants, have been tested with a range of amino acids. In each case, the rates of reaction with 0.2 mM l-amino acid and with the racemic mixture at 0.4 mM were compared, so that the starting concentration of the active substrate was kept constant. Although the d-amino acids are not substrates, they were inhibitory in all cases. The extent of inhibition, however, varied greatly from compound to compound and among the mutants. With the N145L mutant and dl 4-O-Me-Phe, the equimolar d-enantiomer gave 83.2% inhibition, and with the wild-type enzyme there was 86.7% inhibition with racemic norleucine. By contrast, with these same substrates the N145V mutant showed less than 9% and 24% inhibition respectively. The N145A mutant was selected for use with dl-4-Cl-Phe. The pH was decreased from the enzyme's optimum of 10.4 to 9.5 to minimise breakdown of the coenzyme NAD+, and the coenzyme was recycled by molecular oxygen with the assistance of a commercial diaphorase. Reaction on a 200 μmole scale in 20 ml ethanolamine HCl buffer, pH 9.5, with 25 μg N145A enzyme and 100 μg diaphorase, was monitored by chiral HPLC. The l-isomer was removed to an extent of >99% after 40 h, with the d-isomer peak undiminished. The pure d-isomer was isolated from the reaction mixture in 85% overall yield after ion-exchange chromatography.
Synthesis, in vitro biological activity, hydrolytic stability and docking of new analogs of BIM-23052 containing halogenated amino acids
Danalev, Dancho,Borisova, Desislava,Yaneva, Spaska,Georgieva, Maya,Balacheva, Anelia,Dzimbova, Tatyana,Iliev, Ivan,Pajpanova, Tamara,Zaharieva, Zdravka,Givechev, Ivan,Naydenova, Emilia
, p. 1581 - 1592 (2020/11/23)
One of the potent somatostatin analogs, BIM-23052 (DC-23-99) d-Phe-Phe-Phe-d-Trp-Lys-Thr-Phe-Thr-NH2, has established in vitro growth hormone inhibitory activity in nM concentrations. It is also characterized by high affinity to some somatostatin receptors which are largely distributed in the cell membranes of many tumor cells. Herein, we report the synthesis of a series of analogs of BIM-23052 containing halogenated Phe residues using standard solid-phase peptide method Fmoc/OtBu-strategy. The cytotoxic effects of the compounds were tested in vitro against two human tumor cell lines—breast cancer cell line and hepatocellular cancer cell line, as well as on human non-tumorigenic epithelial cell line. Analogs containing fluoro-phenylalanines are cytotoxic in μM range, as the analog containing Phe (2-F) showed better selectivity against human hepatocellular cancer cell line. The presented study also reveals that accumulation of halogenated Phe residues does not increase the cytotoxicity according to tested cell lines. The calculated selective index reveals different mechanisms of antitumor activity of the parent compound BIM-23052 and target halogenated analogs for examined breast tumor cell lines. All peptides tested have high antitumor activity against the HepG2 cell line (IC50 ≈ 100?μM and SI > 5) compared to breast cells. This is probably due to the high permeability of the cell membrane and the higher metabolic activity of hepatocytes. In silico docking studies confirmed that all obtained analogs bind well with the somatostatin receptors with preference to ssrt3 and ssrt5. All target compounds showed high hydrolytic stability at acid and neutral pH, which mimic physiological condition in stomach and human plasma.
Engineered Aminotransferase for the Production of d-Phenylalanine Derivatives Using Biocatalytic Cascades
Walton, Curtis J. W.,Parmeggiani, Fabio,Barber, Janet E. B.,McCann, Jenna L.,Turner, Nicholas J.,Chica, Roberto A.
, p. 470 - 474 (2017/12/15)
d-Phenylalanine derivatives are valuable chiral building blocks for a wide range of pharmaceuticals. Here, we developed stereoinversion and deracemization biocatalytic cascades to synthesize d-phenylalanine derivatives that contain electron-donating or -withdrawing substituents of various sizes and at different positions on the phenyl ring with a high enantiomeric excess (90 to >99 % ee) from commercially available racemic mixtures or l-amino acids. These whole-cell systems couple Proteus mirabilis l-amino acid deaminase with an engineered aminotransferase that displays native-like activity towards d-phenylalanine, which we generated from Bacillus sp. YM-1 d-amino acid aminotransferase. Our cascades are applicable to preparative-scale synthesis and do not require cofactor-regeneration systems or chemical reducing agents.
