24008-77-3Relevant articles and documents
One-Pot Enzymatic Synthesis of d-Arylalanines Using Phenylalanine Ammonia Lyase and l-Amino Acid Deaminase
Zhu, Longbao,Feng, Guoqiang,Ge, Fei,Song, Ping,Wang, Taotao,Liu, Yi,Tao, Yugui,Zhou, Zhemin
, p. 1 - 15 (2018/06/11)
The phenylalanine ammonia-lyase (AvPAL) from Anabaena variabilis catalyzes the amination of substituent trans-cinnamic acid (t-CA) to produce racemic d,l-enantiomer arylalanine mixture owing to its low stereoselectivity. To produce high optically pure d-arylalanine, a modified AvPAL with high d-selectivity is expected. Based on the analyses of catalytic mechanism and structure, the Asn347 residue in the active site was proposed to control stereoselectivity. Therefore, Asn347 was mutated to construct mutant AvPAL-N347A, the stereoselectivity of AvPAL-N347A for d-enantiomer arylalanine was 2.3-fold higher than that of wild-type AvPAL (WtPAL). Furthermore, the residual l-enantiomer product in reaction solution could be converted into the d-enantiomer product through stereoselective oxidation by PmLAAD and nonselective reduction by reducing agent NH3BH3. At optimal conditions, the conversion rate of t-CA and optical purity (enantiomeric excess (eeD)) of d-phenylalanine reached 82% and exceeded 99%, respectively. The two enzymes displayed activity toward a broad range of substrate and could be used to efficiently synthesize d-arylalanine with different groups on the phenyl ring. Among these d-arylalanines, the yield of m-nitro-d-phenylalanine was highest and reached 96%, and the eeD exceeded 99%. This one-pot synthesis using AvPAL and PmLAAD has prospects for industrial application.
Synthesis of chirally pure 2,5-disubstituted diketopiperazines derived from trisubstituted phenylalanines
Danthi, Satyavijayan Narasimhan,Hill, Ronald A.
, p. 835 - 844 (2007/10/03)
Some new chirally pure 2,5-substituted diketopiperazines were synthesized starting from 2-methoxybenzyl alcohol. This multistep synthesis proceeds through the enzymatic synthesis of chirally pure amino acids, protection and dipeptide coupling, cyclization of dipeptide ester formates, and nitration of the resulting diketopiperazines.
A novel hydroxylation of aromatics in a flavin-initiated chain reaction
Mager, Humphrey I. X.,Tu, Shiao-Chun
, p. 6759 - 6766 (2007/10/02)
In aqueous acidic solutions, the 5-ethyl-3-methyllumiflavinium cation 5 was spontaneously transformed into the dihydroflavin pseudobase radical 6 and the flavosemiquinone 7. In attacking an aromatic like phenylalanine, 6 was mainly reconverted to 5 which, ultimately, could lead to an anaerobic accumulation of 7 in yields of 95 ± 5%. In the immediate presence of O2 and/or H2O2, 7 was rapidly and continuously reoxidized to 5 which, consequently, gave a continued production of 6 increasing the hydroxylating ability of the system. The oxidants also had a second distinct effect in converting an intermediate X in a chain reaction to further increase the yields of hydroxyphenylalanines. As illustrated by the results obtained with O2 and H2O2 under comparable conditions, the efficiency of this chain reaction proved to be significantly influenced by the nature of the oxidant. These new findings imply that hydroxyl radicals arising in a homolysis of the O-O bond in a dihydroflavin hydroperoxide should not be taken for granted as the primary attacking species in the hydroxylation of an aromatic. From a practical point of view it is noticed that the hydroxylating ability of the new flavin / H2O2 system surpasses that of any other known, flavin-free chemical system.
