Adenylate kinase: Kinetic behavior in intact cells indicates it is integral to multiple cellular processes
Adenylate kinase: Kinetic behavior in intact cells indicates it is integral to multiple cellular processes
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DOI：
10.1023/a:1006859632730
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发表时间：
1998-07-01
影响因子：
4.3
通讯作者：
Goldberg, ND
中科院分区：
文献类型：
--
作者：
Dzeja, PP;Zeleznikar, RJ;Goldberg, ND
通过 O-18-磷酰氧交换分析监测完整细胞中腺苷酸激酶 (AK) 和肌酸激酶 (CK) 的动力学行为，为更全面地定义这些磷酸转移酶在细胞生物能学中的参与提供了新的视角。 AK 和 CK 的主要功能是它们将 ATP 的利用与根据细胞代谢状态通过糖酵解和/或氧化过程产生的 ATP 结合起来的明显能力。观察结果证明了这一点，即净 AK 加 CK 催化的磷酰基转移总和相当于非收缩性大鼠膈肌中总 ATP 代谢通量的约 95%；在基础条件下，几乎每个新生成的 ATP 分子在利用之前似乎都经过这些磷酸转移酶中的一种或另一种的加工。尽管 CK 负责在基础状态下产生/消耗的大部分 ATP 分子的转移，但随着肌肉收缩的增加或 CK 活性的分级化学抑制，磷酸转移催化从 CK 到 AK 系统存在渐进的、明显补偿性的转变。因此，AK 和 CK 似乎提供相似且相互关联的功能。已经获得的证据表明，某些细胞类型或代谢状态中的高能磷酰基转移也可以由特定的核苷单磷酸激酶和二磷酸激酶以及糖酵解系统固有的磷酸转移能力提供。通过对净 AK 和 CK 催化磷酰基转移的 O-18 交换分析以及对总单向磷酰基通量的 P-31 NMR 分析进行测量表明，CK 或 AK 生成的每个新的能量承载分子随后在到达完整肌肉中 ATP 消耗位点的途中经历约 50 次或更多单向 CK 或 AK 催化磷酸转移。这种多酶催化交换的证据与矢量配体传导机制一致，该机制表明通过 AK 和 CK 系统完成细胞内高能磷酰基转移。 AK 催化的磷酸转移似乎也是影响由腺嘌呤核苷酸调节的离子通道（例如胰岛素分泌细胞中 ATP 抑制的 K+ 通道）运作的代谢信号转导的组成部分；从 ATP 到 ADP 配体状态的转变与rateAK 催化磷酸转移将 ATP (+AMP) 转化为 (2)ADP 密切一致。
Monitoring the kinetic behavior of adenylate kinase (AK) and creatine kinase (CK) in intact cells by O-18-phosphoryl oxygen exchange analysis has provided new perspectives from which to more fully define the involvement of these phosphotransferases in cellular bioenergetics. A primary function attributable to both AK and CK is their apparent capability to couple ATP utilization with its generation by glycolytic and/or oxidative processes depending on cell metabolic status. This is evidenced by the observation that the sum of the net AK- plus CK-catalyzed phosphoryl transfer is equivalent to about 95% of the total ATP metabolic flux in non-contracting rat diaphragm; under basal conditions almost every newly generated ATP molecule appears to be processed by one or the other of these phosphotransferases prior to its utilization. Although CK accounts for the transfer of a majority of the ATP molecules generated/consumed in the basal state there is a progressive, apparently compensatory, shift in phosphotransfer catalysis from the CK to the AK system with increasing muscle contraction or graded chemical inhibition of CK activity. AK and CK appear therefore to provide similar and interrelated functions. Evidence that high energy phosphoryl transfer in some cell types or metabolic states can also be provided by specific nucleoside mono- and diphosphate kinases and by the phosphotransfer capability inherent to the glycolytic system has been obtained. Measurements by O-18-exchange analyses of net AK- and CK-catalyzed phosphoryl transfer in conjunction with P-31 NMR analyses of total unidirectional phosphoryl flux show that each new energy-bearing molecule CK or AK generates subsequently undergoes about 50 or more unidirectional CK-or AK-catalyzed phosphotransfers en route to an ATP consumption site in intact muscle. This evidence of multiple enzyme catalyzed exchanges coincides with the mechanism of vectorial ligand conduction suggested for accomplishing intracellular high energy phosphoryl transfer by the AK and CK systems. AK-catalyzed phosphotransfer also appears to be integral to the transduction of metabolic signals influencing the operation of ion channels regulated by adenine nucleotides such as ATP-inhibitable K+ channels in insulin secreting cells; transition from the ATP to ADP liganded states closely coincides with the rateAK-catalyzes phosphotransfer transforming ATP (+AMP) to (2)ADP.