Activation of Halophilic Nucleoside Diphosphate Kinase by a Non-ionic Osmolyte, Trimethylamine N-Oxide
Activation of Halophilic Nucleoside Diphosphate Kinase by a Non-ionic Osmolyte, Trimethylamine N-Oxide
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非离子渗透剂三甲胺 N-氧化物激活嗜盐核苷二磷酸激酶
DOI：
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
M. Tokunaga
中科院分区：
文献类型：
--
作者：
M. Ishibashi;Kentaro Sakashita;H. Tokunaga;T. Arakawa;M. Tokunaga
嗜盐酶的折叠和活性被认为需要高浓度的盐存在。极端嗜盐古菌灭活的核苷二磷酸酶(NDK)在低盐条件下孵育8天后，无一恢复活性。然而，当与∼2M氯化钠或3M氯化钾孵育时，该酶逐渐恢复活性。令我们惊讶的是，三甲胺N-氧化物(TMAO)也能在4.0M诱导活化。在4M TMAO中复性的NDK的酶活性和二级结构与天然NDK和3.8M氯化钠中复性的NDK的酶活性和二级结构相当。TMAO不是电解液，这意味着浓盐的存在不是绝对的要求，电荷屏蔽或离子结合也不是NDK折叠和激活的唯一因素。虽然氯化钠和TMAO都能有效复性NDK，但它们的作用机制似乎不同：蛋白质浓度和pH对复性的影响存在质的差异，在pH 8.0时，只有在低浓度的氯化钠存在下，4 M TMAO才能使NDK复性。
The folding and activity of halophilic enzymes are believed to require the presence of salts at high concentrations. When the inactivated nucleoside diphosphate kinase (NDK) from extremely halophilic archaea was incubated with low salt media, no activity was regained over the course of 8 days. When it was incubated with ∼2 M NaCl or 3 M KCl, however, it gradually regained activity. To our surprise, trimethylamine N-oxide (TMAO) also was able to induce activation at 4.0 M. The enzyme activity and secondary structure of refolded NDK in 4 M TMAO were comparable with those of the native NDK or the refolded NDK in 3.8 M NaCl. TMAO is not an electrolyte, meaning that the presence of concentrated salts is not an absolute requirement, and that charge shielding or ion binding is not a sole factor for the folding and activation of NDK. Although both NaCl and TMAO are effective in refolding NDK, the mechanism of their actions appears to be different: the effect of protein concentration and pH on refolding is qualitatively different between these two, and at pH 8.0 NDK could be refolded in the presence of 4 M TMAO only when low concentrations of NaCl are included.
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影响因子：
2.9
作者：
Wang, AJ;Bolen, DW
通讯作者：
Bolen, DW
影响因子：
3.4
作者：
ARAKAWA, T;TIMASHEFF, SN
通讯作者：
TIMASHEFF, SN
影响因子：
2.9
作者：
ARAKAWA, T;TIMASHEFF, SN
通讯作者：
TIMASHEFF, SN
影响因子：
2.9
作者：
LIU, YF;BOLEN, DW
通讯作者：
BOLEN, DW