D-amino acid aminotransferase of Bacillus sphaericus. Enzymologic and spectrometric properties.

Intracellular steps of bacterial cell wall peptidoglycan biosynthesis: enzymology, antibiotics, and antibiotic resistance

“…27 The substrate specificity of the B. subtilis and Bacillus YM-1 enzymes is limited to D-alanine, D-glutamate, D-aspartate, D-asparagine, and D-aminobutyrate,60*62 whereas the B. sphaericus enzyme is also active on D-methionine, D-ethionine, D-norleucine, and D-phenylalanine. 61 Determination of the nucleotide sequence of the Bacillus YM-1 D-amino acid aminotransferase gene revealed that the enzyme shares 31 % sequence identity with branched chain Lamino acid aminotransferase from E. coli, suggesting that a change in stereospecificity has occurred during the evolution of one of these two enzymes (Scheme 8).63 X-Ray crystal structures of these enzymes will therefore prove valuable and single crystals of the Bacillus YM-I enzyme have been ~b t a i n e d . ~~ The B. sphaericus enzyme has been the target for suicide inhibitors such as P-halo-~-alanines~~ and D-vinylglycine (1 9),66 which presumably act by similar mechanisms as those detailed above for alanine racemase.…”

The Uncommon Active Site of D-Amino Acid Transaminase from Haliscomenobacter hydrossis: Biochemical and Structural Insights into the New Enzyme

“…The amino acceptor spectrum of Halhy was examined in the overall reaction using D-glutamate as an amino donor ( Table 3 ). Halhy showed the highest activity towards pyruvate and α-ketoglutarate, similar to the most characterized DAATs [ 12 , 13 , 15 ]. Notably, the Halhy activity in the overall reaction diminished with the increase of the length of the α-keto acid side chain.…”

“…No shift of the peak maximum was observed within the pH range 4–10 ( Figure S4 ), showing the stability of the protonated form of the Schiff base up to pH 10. This feature is characteristic of TAs of PLP fold type IV [ 12 , 13 , 24 ].…”

“…In vivo, DAATs catalyze the transfer of the amino group from D-alanine to α-ketoglutarate, producing pyruvate and D-glutamate [ 10 , 11 ]. Only several DAATs are characterized today [ 12 , 13 , 14 , 15 , 16 , 17 ]. In vitro DAATs catalyze transamination between various D-amino acids and keto acids, including α-ketobyturate, indole-3-pyruvate, α-keto-γ-(methylthio)-butyrate, etc.…”

“…[ 16 ]. However, α-ketoglutarate and D-alanine remain the best substrates for most of the characterized DAATs [ 12 , 13 , 15 , 16 ]. DAATs are prominent for the industrial synthesis of optically pure D-amino acids.…”