Production of the Apoptotic Cellular Mediator 4-Methylthio-2-oxobutyric Acid by Using an Enzymatic Stirred Tank Reactor with in Situ Product Removal
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- 作者：Miguel Garcí ; a-Garcí ; a ; Irene Martí ; nez-Martí ; nez ; Á ; lvaro Sá ; nchez-Ferrer ; Francisco Garcí ; a-Carmona
- 刊名：Biotechnology Progress
- 出版年：2008
- 出版时间：February 2008
- 年：2008
- 卷：24
- 期：1
- 页码：187 - 191
- 全文大小：87K
- 年卷期：v.24,no.1(February 2008)
- ISSN：1520-6033
文摘
D-Amino acid oxidase (DAAO) was used to study the oxidative deamination of racemic mixturesof D,L-methionine in its soluble and immobilized forms and thus obtain the corresponding 
-ketoacid. The soluble enzyme form was obtained from a Trigonopsis variabilis CBS 4095 extract,free of L-amino acid oxidase, and was co-immobilized with a 200-fold excess of catalase toavoid the undesirable side reaction of H2O2 with the -keto acid, which would otherwise renderits corresponding decarboxylated acid, the 3-methylthiopropionic acid (MTPA). With thisbiocatalyst, quantitative conversion (>98%) of D-methionine into the -keto acid 4-methylthio-2-oxobutyric acid (MTOB) and into MTPA was achieved using 5 mg·mL-1 of biocatalyst at pH8.0, 25 
C, and pure oxygen at 3 vvm. A stirred tank reactor with in situ product removal(STR-ISPR) was developed to avoid conversion of MTOB into MTPA. The reaction mediumwas re-circulated through a strong anion exchange column (Amberlite IRA-400). This resultedin the complete removal of MTOB from the reaction medium. After the reaction, the reactionproducts were eluted sequentially with water (L-methionine), 10 mM HCl (MTPA), and 0.5 MHCl (MTOB). After elution, MTOB was crystallized to its sodium salt.
-ketoacid. The soluble enzyme form was obtained from a Trigonopsis variabilis CBS 4095 extract,free of L-amino acid oxidase, and was co-immobilized with a 200-fold excess of catalase toavoid the undesirable side reaction of H2O2 with the -keto acid, which would otherwise renderits corresponding decarboxylated acid, the 3-methylthiopropionic acid (MTPA). With thisbiocatalyst, quantitative conversion (>98%) of D-methionine into the -keto acid 4-methylthio-2-oxobutyric acid (MTOB) and into MTPA was achieved using 5 mg·mL-1 of biocatalyst at pH8.0, 25 C, and pure oxygen at 3 vvm. A stirred tank reactor with in situ product removal(STR-ISPR) was developed to avoid conversion of MTOB into MTPA. The reaction mediumwas re-circulated through a strong anion exchange column (Amberlite IRA-400). This resultedin the complete removal of MTOB from the reaction medium. After the reaction, the reactionproducts were eluted sequentially with water (L-methionine), 10 mM HCl (MTPA), and 0.5 MHCl (MTOB). After elution, MTOB was crystallized to its sodium salt.