875-74-1Relevant articles and documents
Formation of Quasi-racemic Diastereoisomeric Salts as a Structural Cause for Efficient Optical Resolution
Fogassy, Elemer,Kozma, David
, p. 5069 - 5070 (1995)
During optical resolutions, when the resolving agent is structurally similar to the racemate, very efficient resolution can be achieved, because of the formation of quasi-racemic diastereoisomeric salts, in which the enantiomers have opposite configuration.
The Methyl Ester of α-Aminophenylacetic Acid: pH-Dependence and Phosphate Catalysis of Hydrolysis
Blinkovsky, Alexander M.,Galaev, Igor Yu.,Svedas, Vytas K.
, p. 1537 - 1540 (1986)
The dependence of the rate of spontaneous (non-enzymic) hydrolysis of α-aminophenylacetic acid methyl ester on the acidity of a medium was studied over the pH range 0.95-11.6.The mono- and dianion of phosphate was found to have a catalytic effect on this reaction, according to the mechanism of general base catalysis.Catalysis of the protonated substrate from hydrolysis by different phosphate ions, the second molecule of water, and the hydroxide ion follows the Broensted catalysis law with the slope 0.60.At a strong alkaline pH, phosphate slows down the ester hydrolysis, probably due to the formation of an ester-phosphate complex; the calculated dissociation constant is 4.2xE-3M, while the ratio of the hydrolysis rate constants for free ester and its phosphate complex is 7.7.
D-Phenylglycine aminotransferase (d-PhgAT)-substrate scope and structural insights of a stereo-inverting biocatalyst used in the preparation of aromatic amino acids
Akhtar, M. Kalim,Campopiano, Dominic J.,De Cesare, Silvia,Loake, Gary J.,Marles-Wright, Jon,Serpico, Annabel
, p. 6533 - 6543 (2020/11/13)
Enantiopure amines are key building blocks in the synthesis of many pharmaceuticals, so a route to their production is a current goal for biocatalysis. The stereo-inverting d-phenylglycine aminotransferase (d-PhgAT), isolated from Pseudomonas stutzeri ST-201, catalyses the reversible transamination from l-glutamic acid to benzoylformate, yielding α-ketoglutarate and d-phenylglycine (d-Phg). Detailed kinetic analysis revealed a range of amine donor and acceptor substrates that allowed the synthesis of enantiopure aromatic d-amino acids at a preparative scale. We also determined the first X-ray crystal structure of d-PhgAT with its bound pyridoxal 5′-phosphate (PLP) cofactor at 2.25 ? resolution. A combination of structural analysis and site-directed mutagenesis of this class III aminotransferase revealed key residues that are potentially involved in the dual substrate recognition, as well as controlling the stereo-inverting behaviour of d-PhgAT. Two arginine residues (Arg34 and Arg407) are involved in substrate recognition within P and O binding pockets respectively. These studies lay the foundation for further enzyme engineering and promote d-PhgAT as a useful biocatalyst for the sustainable production of high value, aromatic d-amino acids. This journal is
Ultrasound-Controlled Chiral Separation of Four Amino Acids and 2,2,2-Trifluoro-1-(9-anthryl)ethanol
Lee, Jae Hwan,Ryoo, Jae Jeong
, p. 146 - 149 (2019/02/07)
Chiral separation of 4-hydroxyphenylglycine, phenylglycine, tryptophan, methionine, and 2,2,2-trifluoro-1-(9-anthryl)ethanol (TFAE) was performed under ultrasound reduction at room temperature and high temperature (50 °C). At high temperature (50 °C), both α and Rs were improved slightly under ultrasound reduction as compared to those under non-ultrasonic and ultrasonic irradiation (50 watt/L) conditions. Even at low temperatures, the largest α was observed under ultrasound reduction conditions, except in the case of methionine. However, at low temperature, Rs was reduced under ultrasound (50 watt/L) irradiation, but was improved under ultrasound reduction rather than under the continuous ultrasonic irradiation. Similar to the fact that gradient elution (based on solvent polarity) can improve α, ultrasound reduction can improve α and Rs. Ultrasound reduction is demonstrated to aid the rapid separation of chiral compounds with improved resolution, especially, at high temperatures. Although chromatographic separation using ultrasound has been rarely dealt with until now, ultrasound can be used as an external field in chromatography.
