Highly selective synthesis of d-amino acids via stereoinversion of corresponding counterpart by an in vivo cascade cell factory

Table 1 Stereoinversion rates of various l-amino acids using E. coli pET-21b-MBP-laad/pET-28a-dapdh-fdh

Substrate	E. coli pET-21b-MBP-laad/pET-28a-dapdh-fdh whole-cell biocatalyst
Substrate	Conversion (%)	Optical purity (% ee)^a
l-Leucine	73.3	> 99
l-Glutamic acid	100	> 99
l-Lysine	51.5
l-Methionine	100	> 99
l-Norvaline	61.8	> 99
l-Tyrosine	45.3	> 99
l-Phenylalanine	100	> 99
l-Tryptophan	44.6
l-Homophenylalanine	100	> 99
2-Chloro-l-phenylalanine	100	> 99
3-Chloro-l-phenylalanine	100	> 99
4-Chloro-l-phenylalanine	100	> 99
4-Methyl-l-phenylalanine	67.4

Reaction conditions: 30 mM substrate, 3 mM NADP⁺, 60 mM ammonium formate were added to 50 mM Tris-HCl buffer (pH 9.0). The concentration of E. coli pET-21b-MBP-laad/pET-28a-dapdh-fdh was 75 mg/mL wet cells. The reactions were carried out at 30 °C and 220 rpm for 24 h.
^aOptical purity (%ee) was determined by HPLC after FDAA derivatization.

ISSN: 1475-2859