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首页> 外文期刊>The FEBS journal >Evidence of a new phosphoryl transfer system in nucleotide metabolism
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Evidence of a new phosphoryl transfer system in nucleotide metabolism

机译：核苷酸代谢中新的磷酰基转移系统的证据

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摘要

Crude rat liver extract showed AMP-AMP phosphotransferase activity which, on purification, was ascribed to a novel interaction between adenylate kinase, also known as myokinase (EC 2.7.4.3), and adenosine kinase (EC 2.7.1.20). The activity was duplicated using the same enzymes purified from recombinant sources. The reaction requires physical contact between myokinase and adenosine kinase, and the net reaction is aided by the presence of adenosine deaminase (EC 3.5.4.4), which fills the gap in the energy balance of the phosphoryl transfer and shifts the equilibrium towards ADP and inosine synthesis. The proposed mechanism involves the association of adenosine kinase and myokinase through non-covalent, transient interactions that induce slight conformational changes in the active site of myokinase, bringing two already bound molecules of AMP together for phosphoryl transfer to form ADP. The proposed mechanism suggests a physiological role for the enzymes and for the AMP-AMP phosphotransferase reaction under conditions of extreme energy drain (such as hypoxia or temporary anoxia, as in cancer tissues) when the enzymes cannot display their conventional activity because of substrate deficiency.
机译：粗制大鼠肝脏提取物显示AMP-AMP磷酸转移酶活性，纯化后可归因于腺苷酸激酶（也称为肌激酶）（EC 2.7.4.3）与腺苷激酶（EC 2.7.1.20）之间的新型相互作用。使用从重组来源纯化的相同酶复制活性。该反应需要肌激酶和腺苷激酶之间的物理接触，并且净反应是通过腺苷脱氨酶的存在（EC 3.5.4.4）来进行的，这填补了磷酸转移的能量平衡的空白，并使平衡向ADP和肌苷转移合成。拟议的机制涉及腺苷激酶和肌激酶通过非共价，短暂的相互作用而缔合，这些相互作用在肌激酶的活性位点引起轻微的构象变化，使两个已经结合的AMP分子聚集在一起，进行磷酰基转移，形成ADP。当由于底物缺乏而使酶无法显示其常规活性时，在极端能量消耗（如缺氧或暂时缺氧，如在癌组织中）的条件下，拟议的机制表明了酶的生理作用和AMP-AMP磷酸转移酶反应的生理作用。

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