A Novel Method for γ-Aminobutyric Acid Biosynthesis Using Glutamate Decarboxylase Entrapped in Polyvinyl Alcohol–Sodium Alginate Capsules
2023
Fei Zhu | Sheng Hu | Weirui Zhao | Lehe Mei
&gamma:-aminobutyric acid (GABA) has essential physiological functions in the human body. A novel method using glutamate decarboxylase (GAD) entrapped in polyvinyl alcohol (PVA)-sodium alginate (SA) capsules provides a green biological strategy for GABA synthesis. In this investigation, the stability range of immobilized GAD was effectively broadened, and immobilized GAD could be repeatedly used as a batch and fixed-bed column catalyst. The immobilized enzymes were stable and retained 89% of their activity in a pH range of 4.0&ndash:5.6, while there was an approximately 50% decrease in free GAD activity in the pH range of 4.8 ±: 0.4. The immobilized GAD affinity to the substrate improved, and this was evidenced by the apparent decrease in Km to 13.3 mmol/L from the 30.9 mmol/L for free GAD. The immobilized GAD retained >:90.6% activity after eight cycles and a near-100% enzyme activity retention after 120 h of a continuous fixed-bed column catalyst operation. This study has thus presented an effective PVA&ndash:SA&ndash:GAD immobilization method that could be used to continuously scale-up GABA biosynthesis.
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