Production of l-theanine using glutaminase encapsulated in carbon-coated mesoporous silica with high pH stability

A new enzymatic process for production of l-theanine was presented using glutaminase combined with immobilization technique on carbon-coated mesoporous silica (carbon/SBA-15). For the attempt to enhance the durability against high pH conditions, the pore surface of mesoporous silica SBA-15 was coated with a thin layer of carbon. Carbon coating was done by addition of 2,3-dihydroxynaphthalene (DN) on the pore surface, followed by a dehydration reaction between surface silanol groups in SBA-15 and hydroxyl groups of DN molecules, and further carbonization of DN. A glutaminase was confined in nanospace (about 5 nm) of carbon/SBA-15. The resulting product, glutaminase/carbon/SBA-15, successfully catalyzed the reaction for production of l-theanine under high pH conditions.

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► The pore surface of SBA-15 was coated with an extremely thin layer of carbon.
► The stability of SBA-15 toward high pH has successfully increased by coating it with carbon.
► The Glu/carbon/SBA-15 catalyzed the reaction for production of l-theanine under high pH conditions.