Department of Biochemistry, Government College University Faisalabad, Pakistan.
Department of Chemistry, Government College University Faisalabad, Pakistan.
Int J Biol Macromol. 2022 Nov 1;220:683-691. doi: 10.1016/j.ijbiomac.2022.08.101. Epub 2022 Aug 17.
An extracellular pectinase from a mixed consortium of Bacillus sp. (BSP) was immobilized onto graphene oxide/chitosan composite (GO/CS) through covalent binding to enhance its recycling and operational stability features. Different parameters were optimized, including cross-linker concentration (%), time, pH, and GO/CS-pectinase ratios. GO/CS-pectinase was further characterized by FT-IR and XRD. The activity of GO/CS-pectinase was reached up to 804 μmolmin with an immobilization efficiency of 80.64 ± 1.15 % under optimum conditions. GO/CS-pectinase exhibited a 3.0-folds higher half-life (t) than free pectinase at 50, 55, and 60 °C, respectively. The V and K values of GO/CS-pectinase were found to be nearly equal to the free pectinase indicating that conformational flexibility was retained. K, t, ∆G*, ∆H*, and ∆S* of both free pectinase and GO/CS-pectinase was 0.0339 & 0.0721 min, 9.62 and 40.44 min, 81.35, 90.72 kJmol, 47.098 & 63.635 kJmol, -102.86 & -81.340 Jmole K. SEM morphological analysis further confirmed the successful binding of pectinase with GO/CS, which retained about 92 % of its original catalytic activity after ten consecutive reaction cycles. Finally, GO/CS-pectinase was employed for guava juice clarification which exhibited the turbidity reduction up to 81 % after 75 min of treatment.
一种来自 Bacillus sp.（BSP）混合菌的细胞外果胶酶通过共价结合固定在氧化石墨烯/壳聚糖复合材料（GO/CS）上，以提高其回收和操作稳定性。优化了不同的参数，包括交联剂浓度（%）、时间、pH 值和 GO/CS-果胶酶的比例。通过傅里叶变换红外光谱（FT-IR）和 X 射线衍射（XRD）进一步对 GO/CS-果胶酶进行了表征。在最佳条件下，GO/CS-果胶酶的活性达到 804 μmolmin，固定化效率为 80.64±1.15%。与游离果胶酶相比，GO/CS-果胶酶在 50、55 和 60°C 下的半衰期（t）分别提高了 3.0 倍。GO/CS-果胶酶的 V 和 K 值与游离果胶酶几乎相等，表明构象灵活性得以保留。游离果胶酶和 GO/CS-果胶酶的 K、t、∆G*、∆H和∆S分别为 0.0339 和 0.0721 min、9.62 和 40.44 min、81.35 和 90.72 kJmol、47.098 和 63.635 kJmol、-102.86 和-81.340 Jmole·K。扫描电子显微镜（SEM）形貌分析进一步证实了果胶酶与 GO/CS 的成功结合，经过十次连续反应循环后，其保留了约 92%的原始催化活性。最后，将 GO/CS-果胶酶用于番石榴汁的澄清，处理 75 min 后浊度降低了 81%。
