Abstract:

To improve significantly the biosynthesis of isovaleryl-L-carnitine catalyzed by lipase needs to select an efficient and suitable reaction medium that is not only polar but also hydrophobic. [Bmim]PF6, which can meet the above two requirements, was applied as the reaction medium in the present study. The effects of 7 key reaction conditions on the biosynthesis of isovaleryl-L-carnitine were investigated. The optimal reaction conditions obtained were as follows: Novozyme 435 as the catalyst, initial water activity 0.22, molar ratio of isovaleric acid to L-carnitine 4:1, lipase amount 50 mg (in the reaction system containing 0.4 mmol of L-carnitine and 1.6 mmol of sovaleric acid), molecular sieve amount (added at the beginning of the reaction) 200 mg, rotation speed of shaking table 200 r/min, temperature 60 ℃, and reaction duration 40 h. Under these conditions, the product yield reached 59.61%, which is higher than that in reaction medium of acetonitrile.

Key words: L-carnitine, isovaleryl-L-carnitine, lipase, [Bmim]PF6, ionic liquid