Tokunaga Hiroko, Oda Yuuki, Yonezawa Yasushi, Arakawa Tsutomu, Tokunaga Masao
Applied and Molecular Microbiology, Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan.
Protein Pept Lett. 2006;13(5):525-30. doi: 10.2174/092986606776819628.
A halophilic nucleoside diphosphate kinase from a moderate halophile, Halomonas sp. 593 (593NDK), was found to be resistant to heat treatment, as indicated by the high level of activity recovery after heating at high temperatures. This is due to reversibility of thermal unfolding, not the high melting temperature, of the protein. The highly homologous NDK from non-halophilic organism, Pseudomonas aeruginosa, showed instability against heat treatment. Chimeric molecules consisting of each half of these two NDKs were constructed and characterized for their heat stability. The results showed that the N-terminal half of 593NDK contributes to the heat stability of the proteins. We discuss the possible reason for the observed difference in resistance to heat treatment between the 593NDK and PaNDK and between two chimeric proteins.
从嗜盐嗜温菌盐单胞菌属593株（593NDK）中分离出的一种嗜盐核苷二磷酸激酶，经高温加热后仍具有较高的活性恢复水平，表明其对热处理具有抗性。这是由于蛋白质热解折叠的可逆性，而非其高熔点温度。来自非嗜盐生物铜绿假单胞菌的高度同源的核苷二磷酸激酶对热处理表现出不稳定性。构建了由这两种核苷二磷酸激酶各一半组成的嵌合分子，并对其热稳定性进行了表征。结果表明，593NDK的N端一半对蛋白质的热稳定性有贡献。我们讨论了观察到的593NDK和铜绿假单胞菌核苷二磷酸激酶（PaNDK）以及两种嵌合蛋白之间对热处理抗性差异的可能原因。
