Food Engineering and Technology Department, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga, Mumbai 400 019, India.
Food Engineering and Technology Department, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga, Mumbai 400 019, India.
Food Chem. 2014 May 1;150:9-16. doi: 10.1016/j.foodchem.2013.10.127. Epub 2013 Nov 1.
Catechin was oligomerized using free laccase and laccase-gum Arabic conjugate. The process of oligomerization was optimized with respect to solvent, ratio of solvent to buffer (0.2:10 to 1:10), pH of buffer (3-10), enzyme (575-18,400 U/mg) and substrate concentration (1-7mM). Maximum production of oligomer was observed in methanol at ratio 0.6:10 of methanol:buffer of pH 5 using 2300 U/mg of laccase and 5mM of catechin. The laccase-gum Arabic conjugate showed lower activity but higher stability than free laccase in methanol. Free laccase produced cross linked water-insoluble oligomer, whereas conjugated laccase produced linear water-soluble oligomer. The linear water-soluble oligomer showed higher antioxidant activity, as determined by the DPPH assay, and reducing power as compared to monomer making it suitable for biological applications. The molecular weight of the linear oligomer was found to be 13.14kDa, which suggested it to be composed of 45 monomer units. Further characterizations of linear and cross linked oligomer were done using FTIR and differential scanning calorimetry.
儿茶素使用游离漆酶和漆酶-阿拉伯胶缀合物进行低聚化。从溶剂种类、溶剂与缓冲液比例（0.2:10 至 1:10）、缓冲液 pH 值（3-10）、酶（575-18400 U/mg）和底物浓度（1-7mM）等方面对低聚化过程进行了优化。在甲醇中，当甲醇与缓冲液的比例为 0.6:10、pH 值为 5 时，使用 2300 U/mg 漆酶和 5mM 儿茶素，观察到低聚产物的最大产量。漆酶-阿拉伯胶缀合物在甲醇中的活性虽低于游离漆酶，但稳定性更高。游离漆酶产生交联的不溶性低聚物，而缀合漆酶则产生线性水溶性低聚物。与单体相比，线性水溶性低聚物通过 DPPH 测定法显示出更高的抗氧化活性和还原能力，使其更适用于生物应用。线性低聚物的分子量为 13.14kDa，表明其由 45 个单体单元组成。进一步使用傅里叶变换红外光谱和差示扫描量热法对线性和交联低聚物进行了表征。
