Graduate Institute of Food Science & Technology, National Taiwan University , No. 1, Sec. 4, Roosevelt Road, Taipei, Taiwan.
J Agric Food Chem. 2012 Dec 26;60(51):12540-6. doi: 10.1021/jf304405t. Epub 2012 Dec 13.
A catalytic system for deglycosylation of isoflavone in black soybean milk was established. β-Glucosidase which was covalently immobilized onto the glass microspheres exhibited a significant efficiency for the conversion of pNPG to p-nitrophenol over other carriers. The optimum temperature for pNPG hydrolysis was 40 °C, and complete reaction can be reached in 30 min. Operational reusability was confirmed for more than 40 batch reactions. Moreover, the storage stability verification demonstrated that the glass microsphere catalytic system was capable of sustaining its highest catalytic activity for 40 days. The kinetic parameters, including rate constant (K) at which isoflavone glycosides deglycosylation were determined, the time (τ(50)) in which 50% of isoflavone glycosides deglycosylation was reached, and the time (τ(complete)) required to achieve complete isoflavone glycosides deglycosylation, were 0.35 ± 0.04 min(-1), 2.04 ± 0.25 min, and 30 min (for daidzin) and 0.65 ± 0.03 min(-1), 1.19 ± 0.08 min, and 20 min (for genistin), respectively. HPLC results revealed that this enzyme system took only 30 min to reach complete isoflavone deglycosylation and the aglycone content in the total isoflavones in black soymilk was enriched by 51.42 ± 0.17% under a 30 min treatment by the glass microsphere enzymatic system.
建立了一种用于黑豆豆浆中异黄酮脱糖的催化体系。共价固定在玻璃微球上的β-葡萄糖苷酶在其他载体上对 pNPG 转化为对硝基苯酚表现出显著的转化效率。pNPG 水解的最佳温度为 40°C，完全反应可在 30 分钟内达到。经过超过 40 批反应证实了操作的可重复使用性。此外，储存稳定性验证表明，玻璃微球催化体系能够维持其最高催化活性长达 40 天。动力学参数，包括异黄酮糖苷脱糖的速率常数（K）、达到 50%异黄酮糖苷脱糖的时间（τ(50)）和达到完全异黄酮糖苷脱糖所需的时间（τ(complete)），分别为 0.35±0.04 min(-1)、2.04±0.25 min 和 30 min（大豆苷）和 0.65±0.03 min(-1)、1.19±0.08 min 和 20 min（染料木苷）。HPLC 结果表明，该酶体系仅需 30 分钟即可达到完全异黄酮脱糖，而玻璃微球酶体系处理 30 分钟后，黑豆浆中总异黄酮的苷元含量富集了 51.42±0.17%。
