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Cross‐linked enzyme aggregates of recombinant cyclodextrin glycosyltransferase for high‐purity β‐cyclodextrin production

Zhang, Jianguo, Li, Mengla, Mao, Hongli
Journal of chemical technology and biotechnology 2019 v.94 no.5 pp. 1528-1533
beta-cyclodextrin, biocatalysts, crosslinking, cyclomaltodextrin glucanotransferase, gamma-cyclodextrin, genes, glutaraldehyde, mutation, potato starch, starch
BACKGROUND: High‐purity α‐, β‐, or γ‐cyclodextrin (CD) production using cyclodextrin glycosyltransferase (CGTase) as biocatalyst to cyclize starch is advantageous owing to its low cost of purification and product specificity. Several approaches have been investigated to enhance product specificity of CGTase, such as new CGTase isolation, CGTase gene (cgt) mutation, and chemical addition. RESULTS: Recombinant CGTase was cross‐linked by glutaraldehyde to obtain cross‐linked enzyme aggregates of recombinant CGTase (CLEA‐CGTase) at 85 °C because free CGTase showed high product specificity at 85 °C. The CLEA‐CGTase was prepared under the conditions 75 U mL⁻¹ CGTase with 0.1% (v/v) glutaraldehyde for 10 min at 85 °C after optimization first, and produced a high proportion of β‐CD from soluble starch at 50 °C in the conversion system. The conversion process was carried out with 10 to 200 U mL⁻¹ CLEA‐CGTase, resulting in 100% β‐CD from soluble starch after 420 min conversion of the potato starch solution at 50 °C. And the proportion of β‐CD was still higher than 90% when 8000 U mL⁻¹ CLEA‐CGTase was added. CONCLUSIONS: CLEA technology maintained CGTase conformation of 85 °C, and produced a high proportion of β‐CD at 50 °C. This research showed the CLEA technology kept the conformation of enzyme for specific product production. © 2018 Society of Chemical Industry