Construction and optimization of a biocatalytic route for the synthesis of neomenthylamine from menthone

Bioresources and Bioprocessing

Table 1 Asymmetric synthesis of (+)-neomenthylamine using VfTA with different amino donors

Enzyme	DL-Ala		Isopropylamine		2-Pentanamine
Enzyme	Conv. (%)^a	d.e. (%)^b	Conv. (%)^a	d.e. (%)^b	Conv. (%)^a	d.e. (%)^b
VfTA	0.9	79 (3S, 4S)	3.8	82 (3S, 4S)	2.1	80 (3S, 4S)

^aConversion and the value of diastereomeric excess was determined by GC–MS on an achiral phase. The screening reaction system (1 mL) consists of potassium salt phosphate buffer (100 mM KPB pH 8.0), 5 mM (−)-menthone, 50 mM DL-Ala or isopropylamine or 2-pentanamine, 0.5 mM pyridoxal-5′-phosphate (PLP), 15 g_cdw L⁻¹ whole cells, 10% (v/v) dimethyl sulfoxide. All the reaction mixtures were shaken for 24 h at 30 °C and 1000 rpm in a high-speed shaker
^b D.e. (%) = \(|\frac{\left[\left(3{\text{S}}, 4{\text{S}}\right)+(3{\text{R}}, 4{\text{S}})\right]-[\left(3{\text{S}}, {\text{R}}\right)+(3{\text{R}}, 4{\text{R}})]}{\left[\left(3{\text{S}}, 4{\text{S}}\right)+(3{\text{R}}, 4{\text{S}})\right]+\left[\left({3}{\text{S}}, 4{\text{R}}\right)+(3{\text{R}}, 4{\text{R}})\right]}|\)