1. Supplementary Fig. S2 Elution profiles of amino acid derivatives in a UPLC system. The enzyme (1 μg) was incubated with 10 mM D -amino acid (2.5 mM D -Tyr) in 0.1 M potassium phosphate buffer (pH 7.0) containing 40 μM PLP in a total volume of 0.1 ml for 6 h at 80  C. As a control, incubation was also performed without the enzyme. The reaction mixtures were then treated with TCA and neutralized with NaOH. D - and L - amino acids were derivatized with OPA -NAC or OPA-NBC for diastereoisomerization (Aswad 1984; Hashimoto et al. 1992), after which the derivatives were separated using an AccQ-Tag Ultra column (Waters) on a UPLC system and detected using a fluorescence detector (excitation: at 350 nm and emission at 450 nm), as described by Mutaguchi et al. (2013). Each figure shows an elution profile of the samples. The horizontal and vertical axes are the retention time (min) and fluorescence intensity, respectively. Peaks in each profile show the amino acid derivatives after incubation with the enzyme (black line) and without the enzyme (blue line). In the control, only the derivative obtained from the D -amino acid was detected. After incubation with the enzyme, the peaks for the derivatives from the L -forms of Met, Leu, Phe, Ala, Ser, Ile, Val, Trp and Tyr were clearly detected along with the decreasing peaks for the derivatives from the D -forms. Peaks for L -Asp and L -Glu were not detected, indicating they were inert as substrates.

2. D -Met L -Met D -Leu L -Leu D -Phe L -Phe

3. D -Ala L -Ala D -Ser L -Ser D -allo-Ile L -Ile

4. D -Val L -Val D -Trp L -Trp D -Tyr L -Tyr

5. D -Asp D -Glu