*2.6. The Substrate Specificity Analysis and Kinetic Parameters of rPsLeuDH*

The substrate specificity analysis of rPsLeuDH was listed in Table 3. It could catalyze and utilize five substrates, indicating that rPsLeuDH possessed a broad spectrum of substrates in catalytic oxidation reaction. L-leucine was the most suitable substrate for rPsLeuDH, which was the similar with other microbial LeuDH [6,22]. The kinetic parameters of rPsLeuDH were determined. *K*<sup>m</sup> and *V*<sup>m</sup> of L-leucine were calculated as 0.33 mM and 15.24 μmol/min·mg, respectively. Besides, the *k*cat value of L-leucine was 30.13/s, demonstrating that rPsLeuDH had a high affinity to substrates and was conducive to improving catalytic efficiency at low temperature.

**Table 3.** Substrate specificity analysis of rPsLeuDH.

