Stereoselective biotransformation of racemic mandelic acid using immobilized laccase and (S)-mandelate dehydrogenase

Xing Chen; Chengli Yang; Peng Wang; Xuan Zhang; Bingxin Bao; Dali Li; Ruofu Shi

doi:10.1186/s40643-016-0135-3

Stereoselective biotransformation of racemic mandelic acid using immobilized laccase and (S)-mandelate dehydrogenase

Bioresour Bioprocess. 2017;4(1):2. doi: 10.1186/s40643-016-0135-3. Epub 2017 Jan 3.

Authors

Xing Chen¹, Chengli Yang¹, Peng Wang¹, Xuan Zhang¹, Bingxin Bao¹, Dali Li¹, Ruofu Shi¹

Affiliation

¹ Department of Bioengineering, Nanjing University of Science and Technology, Xiaolingwei 200, Nanjing, 210094 People's Republic of China.

Abstract

Objectives: (S)-Mandelate dehydrogenase (SMDH) and laccase were immobilized on chitosan. The bi-enzymatic system with immobilized SMDH and immobilized laccase was taken to catalyze the stereoselective transformation of racemic mandelic acid and (R)-mandelic acid was obtained from its racemic mixture.

Results: Characteristics of the immobilized enzymes were valuated. The optimum pH and temperature of the immobilized SMDH were found to be pH 3.4 and 45 °C, and these of the immobilized laccase were about pH 6.0 and 55 °C, respectively. The K_m value of the immobilized SMDH for racemic mandelic acid was 0.27 mM and that of the immobilized laccase for ferrocyanide was 0.99 mM. The thermal and storage stabilities of these enzymes were improved with immobilization. The enantiomeric purity of the bi-enzymatically produced (R)-mandelic acid was determined to be over 99%.

Conclusion: The immobilized bi-enzymatic system for the stereoselective transformation of racemic mandelic acid showed higher productivity, faster reaction velocity, and more stable catalytic ability.Graphical abstract.

Keywords: (S)-Mandelate dehydrogenase; Bi-enzymatic system; Biocatalysis; Chitosan; Immobilization; Laccase.