Acharya Chitrangada, Kumar Veerendra, Sen Ramkrishna, Kundu Subhas C
Department of Biotechnology, Indian Institute of Technology, Kharagpur, India.
Biotechnol J. 2008 Feb;3(2):226-33. doi: 10.1002/biot.200700120.
L-DOPA (3,4-dihydroxyphenyl-L-alanine), one of the most important intermediates in the melanin biosynthesis pathway, is used for the treatment of Parkinson's disease. With a view of developing a cheaper and more effective method for the bioconversion of tyrosine to L-DOPA, the potential and performance of a novel fibrous matrix prepared from Bombyx mori silk protein fibroin were evaluated for the immobilization of tyrosinase. Cross-linkage between fibroin and tyrosinase using glutaraldehyde was evident from Fourier transform infra red spectroscopy. Maximum product formation occurred when 1000 U enzyme was immobilized on 20 mg fibroin. The optimum conditions for maximal L-DOPA production using immobilized tyrosinase were 40 degrees C and pH 5.5, conditions that caused a 50% loss of free enzyme activity. Immobilized tyrosinase also showed to have a higher degree of stability during storage and it retained 80% of its original activity after repeated reuses. The efficiency of this immobilized tyrosinase system to produce L-DOPA was high, as evident from a high effectiveness factor, between 0.7 and 0.8, thereby making this method feasible for the large-scale production of L-DOPA.
左旋多巴（3,4-二羟基苯丙氨酸）是黑色素生物合成途径中最重要的中间体之一，用于治疗帕金森病。为了开发一种更廉价、更有效的将酪氨酸生物转化为左旋多巴的方法，对由家蚕丝蛋白纤维制备的新型纤维基质固定化酪氨酸酶的潜力和性能进行了评估。傅里叶变换红外光谱表明，纤维蛋白和酪氨酸酶之间通过戊二醛发生了交联。当1000 U酶固定在20 mg纤维蛋白上时，产物形成量最大。使用固定化酪氨酸酶生产最大量左旋多巴的最佳条件是40℃和pH 5.5，这些条件会使游离酶活性损失50%。固定化酪氨酸酶在储存期间也表现出更高的稳定性，重复使用后仍保留其原始活性的80%。从0.7到0.8的高效因子可以看出，这种固定化酪氨酸酶系统生产左旋多巴的效率很高，从而使该方法适用于大规模生产左旋多巴。
