1. Structures of D-amino-acid amidase complexed with L-phenylalanine and with L-phenylalanine amide: insight into the D-stereospecificity of D-amino-acid amidase from Ochrobactrum anthropi SV3
Seiji Okazaki, Atsuo Suzuki, Tsunehiro Mizushima, Hidenobu Komeda, Yasuhisa Asano, Takashi Yamane Acta Crystallogr D Biol Crystallogr. 2008 Mar;64(Pt 3):331-4. doi: 10.1107/S0907444907067479. Epub 2008 Feb 20.
The crystal structures of D-amino-acid amidase (DAA) from Ochrobactrum anthropi SV3 in complex with L-phenylalanine and with L-phenylalanine amide were determined at 2.3 and 2.2 A resolution, respectively. Comparison of the L-phenylalanine amide complex with the D-phenylalanine complex reveals that the D-stereospecificity of DAA might be achieved as a consequence of three structural factors: (i) the hydrophobic cavity in the region in which the hydrophobic side chain of the substrate is held, (ii) the spatial arrangement of Gln310 O and Glu114 O epsilon2 that fixes the amino N atom of the substrate and (iii) the existence of two cavities that keep the carboxyl/amide group of the substrate near or apart from Ser60 O gamma.
2. Ameliorative effect of chromium-d-phenylalanine complex on indomethacin-induced inflammatory bowel disease in rats
S Nagarjun, Shivsharan B Dhadde, Veeresh P Veerapur, B S Thippeswamy, Baburao N Chandakavathe Biomed Pharmacother. 2017 May;89:1061-1066. doi: 10.1016/j.biopha.2017.02.042. Epub 2017 Mar 11.
Present study was designed to evaluate the effect of chromium-d-phenylalanine complex (Cr (d-phe)3) on indomethacin-induced inflammatory bowel disease (IBD) in rats. Adult Wistar rats were pretreated with vehicle/Cr (d-phe)3 (30, 60 and 90μg/kg, p.o.) for 11days. On day 8 and 9, after one h of the above mentioned treatment, indomethacin (7.5mg/kg/day,s.c.) was administered to induce IBD. On day 12, blood samples were collected from animals for lactate dehydrogenase (LDH) estimation and ileum was isolated for macroscopic scoring, biochemical estimation (lipid peroxidation, reduced glutathione and myeloperoxidase activity) and histopathological study. Administration of indomethacin significantly altered the serum LDH, macroscopic and microscopic appearance and biochemical parameters in ileum tissue. Cr (d-phe)3, at all the tested doses, caused a significant reversal of changes induced by indomethacin. Present study demonstrates the protective effect of Cr (d-phe)3 against indomethacin-induced IBD in rats. The observed protective effect might be attributed to the antioxidant and anti-inflammatory properties of Cr (d-phe)3.
3. AMINO ACID ISOMERIZATION IN THE PRODUCTION OF L-PHENYLALANINE FROM D-PHENYLALANINE BY BACTERIA
I CHIBATA, T TOSA, R SANO Appl Microbiol. 1965 Jul;13(4):618-24. doi: 10.1128/am.13.4.618-624.1965.
To establish an advantageous method for the production of l-amino acids, microbial isomerization of d- and dl-amino acids to l-amino acids was studied. Screening experiments on a number of microorganisms showed that cell suspensions of Pseudomonas fluorescens and P. miyamizu were capable of isomerizing d- and dl-phenylalanines to l-phenylalanine. Various conditions suitable for isomerization by these organisms were investigated. Cells grown in a medium containing d-phenylalanine showed highest isomerization activity, and almost completely converted d- or dl-phenylalanine into l-phenylalanine within 24 to 48 hr of incubation. Enzymatic studies on this isomerizing system suggested that the isomerization of d- or dl-phenylalanine is not catalyzed by a single enzyme, "amino acid isomerase," but the conversion proceeds by a two step system as follows: d-pheylalanine is oxidized to phenylpyruvic acid by d-amino acid oxidase, and the acid is converted to l-phenylalanine by transamination or reductive amination.
