Yu Jianyun, Chen Xinxin, Jiang Min, Wang Anming, Yang Linlin, Pei Xiaolin, Zhang Pengfei, Wu Stephen Gang
College of Materials, Chemistry and Chemical Engineering, Hangzhou Normal University Hangzhou 310014 P. R. China
Department of Energy, Environmental and Chemical Engineering, Washington University St. Louis MO 63130 USA.
RSC Adv. 2018 Jan 9;8(5):2357-2364. doi: 10.1039/c7ra12940h.
To develop an efficient and green immobilized biocatalyst for promiscuous catalysis which has a broad scope of applications, hybrid nanoflower (hNF) confined papain as a biocatalyst has been proposed and characterized in this study. hNFs were firstly prepared through mixing CuSO aqueous solution with papain in phosphate saline (PBS) at room temperature. The resulting hNFs were characterized by SEM and verified through a hydrolysis reaction with -benzoyl-dl-arginine amide as substrate. Under optimal conditions, this nano-biocatalyst demonstrated a 15-fold hydrolytic activity compared with papain of free form, along with better thermal stability. A series of reaction factors (reaction temperature, time, and solvent) have been investigated for Knoevenagel condensation reactions with hNFs as catalyst. At optimal conditions, product yield of the hNFs catalyzed reaction was 1.3 fold higher than that of the free enzyme with benzaldehyde and acetylacetone as substrates. A few aldehydes and methylene compounds have also been used to test the generality and scope of this new enzymatic promiscuity. To sum up, the obtained hNFs demonstrate better catalytic properties than free papain and the inorganic metal-salt crystal can function as both support and promotor in biocatalysis.
为开发一种具有广泛应用范围的高效绿色固定化生物催化剂用于多催化反应，本研究提出并表征了以混合纳米花（hNF）包裹木瓜蛋白酶作为生物催化剂。首先在室温下将硫酸铜水溶液与木瓜蛋白酶在磷酸盐缓冲液（PBS）中混合制备hNFs。通过扫描电子显微镜（SEM）对所得hNFs进行表征，并以苯甲酰 - dl - 精氨酸酰胺为底物通过水解反应进行验证。在最佳条件下，这种纳米生物催化剂的水解活性比游离形式的木瓜蛋白酶高15倍，并且具有更好的热稳定性。以hNFs为催化剂，研究了一系列反应因素（反应温度、时间和溶剂）对Knoevenagel缩合反应的影响。在最佳条件下，以苯甲醛和乙酰丙酮为底物，hNFs催化反应的产物产率比游离酶高1.3倍。还使用了一些醛类和亚甲基化合物来测试这种新的酶促多催化反应的通用性和范围。总之，所获得的hNFs表现出比游离木瓜蛋白酶更好的催化性能，并且无机金属盐晶体在生物催化中既可以作为载体又可以作为促进剂。
