Wahba Marwa I
Department of Chemistry of Natural and Microbial Products, National Research Centre, El-Behooth St., Dokki, Giza, Egypt.
Centre of Scientific Excellence-Group of Advanced Materials and Nanotechnology, National Research Centre, El-Behooth St., Dokki, Giza, Egypt.
3 Biotech. 2020 Aug;10(8):356. doi: 10.1007/s13205-020-02341-y. Epub 2020 Jul 27.
Polyethyleneimine (PEI) glutaraldehyde-refined calcium pectinate (CaP)-agar beads were presented as improved covalent immobilization matrices. The CaP-agar beads exhibited incremented mechanical stability which facilitated their handling. The beads' concoction and activation processes were honed using the Box-Behnken design which recommended utilizing 5.4% agar, and a 2.95% PEI solution of pH 8.67. The honed CaP-agar beads established a more efficient ionic interaction with PEI which enabled the immobilization of more enzyme while utilizing less PEI than that required to activate the neat CaP beads. Furthermore, the activated CaP-agar beads granted superior operational stability to the immobilized enzyme, β-d-galactosidase (βgal), where it preserved 86.84 ± 0.37% of its precursive activity during its thirteenth reusability round. The CaP-agar immobilized βgal (iβgal) also showed incremented storage stability where it preserved 85.05 ± 3.32% of its precursive activity after 38 days of storage. The thermal stability of the iβgal was shown to be superior to that of the free enzyme as the iβgal exhibited incremented thermodynamic parameters, such as the values, the values, the thermal denaturation activation energy, the enthalpies, and the Gibb's free energies. The βgal's immobilization onto the activated CaP-agar beads also shifted the enzyme's optimal pH from 4.6-5.1 to 3.3-4.9, whereas its optimal temperature was retained at 55 °C. The procured biocatalyst was exploited to efficiently hydrolyze the lactose in whey permeate.
聚乙烯亚胺（PEI）戊二醛精制果胶酸钙（CaP）-琼脂珠被提出作为改进的共价固定化基质。CaP-琼脂珠表现出增强的机械稳定性，便于处理。使用Box-Behnken设计优化了珠子的制备和活化过程，该设计建议使用5.4%的琼脂和pH值为8.67的2.95%的PEI溶液。优化后的CaP-琼脂珠与PEI建立了更有效的离子相互作用，能够固定更多的酶，同时与激活纯CaP珠所需的PEI相比用量更少。此外，活化的CaP-琼脂珠赋予固定化酶β-d-半乳糖苷酶（βgal）优异的操作稳定性，在第13次重复使用过程中，它保留了其初始活性的86.84±0.37%。CaP-琼脂固定化的βgal（iβgal）在储存稳定性方面也有所提高，储存38天后，它保留了其初始活性的85.05±3.32%。iβgal的热稳定性优于游离酶，因为iβgal表现出更高的热力学参数，如 值、 值、热变性活化能、焓和吉布斯自由能。βgal固定在活化的CaP-琼脂珠上也使酶的最佳pH值从4.6-5.1变为3.3-4.9，而其最佳温度保持在55°C。所获得的生物催化剂被用于有效水解乳清渗透物中的乳糖。
