Immobilization of Phenylalanine Ammonia-Lyase on Single-Walled Carbon Nanotubes for Stereoselective Biotransformations in Batch and Continuous-Flow Modes
메타 데이터
바이오화학분류
바이오정밀화학
화학제품
연료
논문
Immobilization of Phenylalanine Ammonia-Lyase on Single-Walled Carbon Nanotubes for Stereoselective Biotransformations in Batch and Continuous-Flow Modes
<P><B>Abstract</B></P><P>Carboxylated single‐walled carbon nanotubes (SwCNT<SUB>COOH</SUB>) were used as a support for the covalent immobilization of phenylalanine ammonia‐lyase (PAL) from parsley by two different methods. The nanostructured biocatalysts (SwCNT<SUB>COOH</SUB>‐PAL<SUP>I</SUP> and SwCNT<SUB>COOH</SUB>‐PAL<SUP>II</SUP>) with low diffusional limitation were tested in the batch‐mode kinetic resolution of racemic 2‐amino‐3‐(thiophen‐2‐yl)propanoic acid (<B>1</B>) to yield a mixture of (<I>R</I>)‐<B>1</B> and (<I>E</I>)‐3‐(thiophen‐2‐yl)acrylic acid (<B>2</B>) and in ammonia addition to <B>2</B> to yield enantiopure (<I>S</I>)‐<B>1</B>. SwCNT<SUB>COOH</SUB>‐PAL<SUP>II</SUP> was a stable biocatalyst (>90 % of the original activity remained after six cycles with <B>1</B> and after three cycles in 6 <SMALL>M</SMALL> NH<SUB>3</SUB> with <B>2</B>). The study of ammonia addition to <B>2</B> in a continuous‐flow microreactor filled with SwCNT<SUB>COOH</SUB>‐PAL<SUP>II</SUP> (2 <SMALL>M</SMALL> NH<SUB>3</SUB>, pH 10.0, 15 bar) between 30–80 °C indicated no significant loss of activity over 72 h up to 60 °C. SwCNT<SUB>COOH</SUB>‐PAL<SUP>II</SUP> in the continuous‐flow system at 30 °C was more productive (specific reaction rate, <I>r</I><SUB>flow</SUB>=2.39 μmol min<SUP>−1</SUP> g<SUP>−1</SUP>) than in the batch reaction (<I>r</I><SUB>batch</SUB>=1.34 μmol min<SUP>−1</SUP> g<SUP>−1</SUP>).</P>