| 3-phenyllactic acid is an important precursor for chemical synthesis, and it was widely used in many fields, such as medicine, chemical industry, biosynthesis and so on. However, the two enantiomers of 3-phenyllactic acid show different biological activities and different applications in pharmaceutical and chemical industry. As a consequence, synthesis of chiral 3-phenyllactic acid is very significant. These could be met by biosynthesis.The method was established to resolve chiral 3-phenyllactic acids by capillary electrophoresis. Using 0.1mol/L phosphate solution (pH5.5) as running buffer and 0.03mol/L hydroxypropyl-β-cyclodextrin as chiral selector, the baseline seperation of 3-phenyllactic acid enantiomers was achieved with resolution of 1.51 by quartz capillary without coating(60cm/75cm×50μm i.d.)and capillary zone electrophoresis under seperation voltage 26kv at 25℃. Based on these results, the methods for qualitative and quantitative analysis of 3-phenyllactic acid were established.The feasibility was analyzed to transforme phenylpyruvic acid to R-3-phenyllactic acid by Staphylococcus haemolyticus T01. S. haemolyticus T01 could reduce asymmetrically phenylpyruvic acid to R-3-phenyllactic acid of 100% enantiomeric excess.The fermentation conditions of S. haemolyticus T01 were studied. The optimal medium was as follows: 2% D-fructose, 0.5% yeast paste, 0.5% NaCl, 0.01%FeSO4?7H2O, and initial pH was adjusted to 7.0. The strain showed highest activity after incubation at 30℃,180r/min for 30h. The specific activity of the enzyme was 0.6265mU/g.The optimal conditions were investigated for bioreduction of phenylpyruvic acid to R-3-phenyllactic acid. With phenylpyruvic acid concentration being 3.0g/L, cell / phenylpyruvic acid ratio being 2.5, and 0.03g/L cetyl pyridinium bromide and 5% glucose added, the conversion rate of phenylpyruvic acid to R-3-phenyllactic acid could reach 46.38% after 16h at 30℃,180r/min in pH 8.0 reaction system(0.05mol/L phosphate solution as buffer).
|
PDF Full Text Request