Diol Dehydratase-Reactivase Is Essential for Recycling of Coenzyme B12 in Diol Dehydratase.
Diol Dehydratase-Reactivase Is Essential for Recycling of Coenzyme B12 in Diol Dehydratase.
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二醇脱水酶重新激活酶对于二醇脱水酶中辅酶 B12 的回收至关重要。
DOI：
10.1021/acs.biochem.5b01023
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发表时间：
2016
期刊：
影响因子：
2.9
通讯作者：
Tobimatsu T.
中科院分区：
文献类型：
--
作者：
Toraya T;Tanokuchi A;Yamasaki A;Nakamura T;Ogura K;Tobimatsu T.
腺苷钴胺依赖二醇和甘油脱水酶的全酶在没有底物的情况下被甘油和o2失活，并伴随着辅酶Co-C键的不可逆裂解。用NADH、ATP和Mg2+（或Mn2+）孵育后，脱氧克雷伯菌粗提取物中失活的holodiol脱水酶和失活的酶·氰钴胺复合体（cyanocobalamin complex）被（重新）激活，表明提取物中存在一个再活化系统。NADH还原体系可用FMNH2代替。将失活全酶或酶·氰钴胺复合物（失活全酶模型）与纯化的重组二醇脱水酶-再激活酶（DD-R）和ATP:cob(I)alamin腺苷转移酶在FMNH2、ATP和Mg2+存在下孵育后，二醇脱水酶活性恢复。在该细菌的三种腺苷转移酶（PduO， EutT和CobA）中，PduO和CobA对游离玉米芯(I)alamin的再激活效率远高于EutT，尽管PduO对游离玉米芯(I)alamin的腺苷转移酶活性最低。这些结果表明：(1)二醇脱水酶的活性是通过由DD- r、PduO腺苷转移酶和还原系统组成的二醇脱水酶再激活系统来维持的；(2)释放因子DD- r是一种紧密结合的假基型辅酶腺钴胺素再激活所必需的；(3)PduO是DD再激活的特异性腺苷化酶，而CobA和EutT是通过自由合成的辅酶来发挥作用的。虽然fmnh2在本研究中主要用作还原剂，但一个天然的还原系统可能由PduS钴胺还原酶和NADH组成。
Holoenzymes of adenosylcobalamin-dependent diol and glycerol dehydratases undergo mechanism-based inactivation by glycerol and O2inactivation in the absence of substrate, which accompanies irreversible cleavage of the coenzyme Co–C bond. The inactivated holodiol dehydratase and the inactive enzyme·cyanocobalamin complex were (re)activated by incubation with NADH, ATP, and Mg2+(or Mn2+) in crude extracts ofKlebsiella oxytoca, suggesting the presence of a reactivating system in the extract. The reducing system with NADH could be replaced by FMNH2. When inactivated holoenzyme or the enzyme·cyanocobalamin complex, a model of inactivated holoenzyme, was incubated with purified recombinant diol dehydratase-reactivase (DD-R) and an ATP:cob(I)alamin adenosyltransferase in the presence of FMNH2, ATP, and Mg2+, diol dehydratase activity was restored. Among the three adenosyltransferases (PduO, EutT, and CobA) of this bacterium, PduO and CobA were much more efficient for the reactivation than EutT, although PduO showed the lowest adenosyltransfease activity toward free cob(I)alamin. These results suggest that (1) diol dehydratase activity is maintained through coenzyme recycling by a reactivating system for diol dehydratase composed of DD-R, PduO adenosyltransferase, and a reducing system, (2) the releasing factor DD-R is essential for the recycling of adenosycobalamin, a tightly bound, prosthetic group-type coenzyme, and (3) PduO is a specific adenosylating enzyme for the DD reactivation, whereas CobA and EutT exert their effects through free synthesized coenzyme. Although FMNH2was mainly used as a reductant in this study, a natural reducing system might consist of PduS cobalamin reductase and NADH.
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钴酰胺辅酶的酶促合成。
DOI：
10.1016/0006-291x(61)90309-6
发表时间：
1961
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
R. Brady;E. G. Castanera;H. A. Barker
通讯作者：
H. A. Barker
从产气杆菌分离的甘油脱水酶的特性，以及脱辅基酶亚基的特性。
影响因子：
1.7
作者：
Z. Schneider;J. Pawelkiewicz
通讯作者：
J. Pawelkiewicz
低溶解度甘油脱水酶，辅酶 B12 依赖性甘油和二醇脱水酶的嵌合酶
影响因子：
2.8
作者：
T. Tobimatsu;Tsuneo Nishiki;Masaya Morimoto;Ryou Miyata;T. Toraya
通讯作者：
T. Toraya
影响因子：
2.9
作者：
Schubert, Heidi L.;Hill, Christopher P.
通讯作者：
Hill, Christopher P.
影响因子：
3.9
作者：
FUJII, K;GALIVAN, JH;HUENNEKENS, FM
通讯作者：
HUENNEKENS, FM