Shah Shweta, Sharma Aparna, Varandani Deepak, Mehta Bodhraj, Gupta Munishwar N
Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
J Nanosci Nanotechnol. 2007 Jun;7(6):2157-60. doi: 10.1166/jnn.2007.786.
The goal of obtaining enzyme forms which show greater stability, higher catalytic efficiency, and reusability has been pursued since last several decades. Some novel biocatalyst designs have been evolved and protein coated micro-crystals (PCMCs) is one of them. Pseudomonas cepacia lipase coated micro-crystals were prepared by simultaneous precipitation of mixture of aqueous lipase solution and salts such as potassium sulphate by organic solvents. This resulted in lipase coated micro-crystals. The structures of micro-crystals were studied by atomic force microscopy (AFM). The AFM picture confirmed the enzyme coating over the potassium sulphate crystals. These PCMCs are in the size range of 500-1000 nm. These enzyme coated micro-crystals showed enhanced transesterification rates. Also, the PCMC were stable at 60 degrees C whereas the free enzyme lost all its activity. The enzyme coated micro-crystals prepared by 50 mg Pseudomonas cepacia lipase gave 96% conversion in 90 min whereas free enzyme gave 8% conversion. Even PCMCs prepared from 3.12 mg lipase gave 90% conversion in 10 h at 60 degrees C where as free lipase was inactive at 60 degrees C.
在过去几十年里，人们一直致力于获得具有更高稳定性、更高催化效率和可重复使用性的酶形式。已经开发出了一些新型生物催化剂设计，蛋白质包覆微晶（PCMCs）就是其中之一。通过用有机溶剂同时沉淀脂肪酶水溶液和盐（如硫酸钾）的混合物来制备洋葱假单胞菌脂肪酶包覆的微晶。这就得到了脂肪酶包覆的微晶。通过原子力显微镜（AFM）研究了微晶的结构。AFM图像证实了硫酸钾晶体上的酶包覆。这些PCMCs的尺寸范围在500 - 1000纳米。这些酶包覆的微晶表现出更高的酯交换率。此外，PCMC在60摄氏度时稳定，而游离酶则失去了所有活性。由50毫克洋葱假单胞菌脂肪酶制备的酶包覆微晶在90分钟内转化率为96%，而游离酶的转化率为8%。即使由3.12毫克脂肪酶制备的PCMC在60摄氏度下10小时内转化率也达到了90%，而游离脂肪酶在60摄氏度时无活性。
