Dzeja P P, Zeleznikar R J, Goldberg N D
Department of Biochemistry, University of Minnesota, Medical School, Minneapolis, Minnesota 55455, USA.
J Biol Chem. 1996 May 31;271(22):12847-51. doi: 10.1074/jbc.271.22.12847.
The kinetics of creatine kinase (CK) and adenylate kinase (AK) activities were monitored in intact diaphragm muscle by 18O phosphoryl oxygen exchange to assess whether these two phosphotransferases provide an interrelated function integral to high energy phosphoryl metabolism. This possibility was examined by quantitating the net rates of CK- and AK-catalyzed phosphoryl transfer in comparison to the total cellular ATP metabolic rate when CK activity in the intact diaphragm muscle was progressively inhibited by 2,4-dinitrofluorobenzene. In noncontracting muscle from untreated rats, net rates of CK- and AK-catalyzed phosphotransfer were equivalent to 88 and 7%, respectively, of the total ATP metabolic rate. These results were compared with reported 31P NMR analyses of total creatine phosphate flux to estimate that each creatine phosphate molecule produced undergoes about 50 unidirectional CK-catalyzed phosphotransfers in transit to an ATP consumption site in the intact muscles. Graded inhibition by 2,4-dinitrofluorobenzene of intracellular CK activity by up to 98% resulted in a progressive shift in phosphotransferase catalysis from the CK to the AK system; the sum of the net rates of phosphoryl transfer by combining the increasing AK and decreasing CK activities continued to approximate the total cellular ATP metabolic rate. These results indicate that in diaphragm muscle CK and AK operate as interrelated cellular high energy phosphoryl transfer systems through which the majority of newly generated ATP is processed prior to its utilization.
通过(^{18}O)磷酰氧交换监测完整膈肌中肌酸激酶（CK）和腺苷酸激酶（AK）活性的动力学，以评估这两种磷酸转移酶是否提供了与高能磷酸代谢不可或缺的相互关联的功能。当完整膈肌中的CK活性被2,4 - 二硝基氟苯逐渐抑制时，通过定量CK和AK催化的磷酰转移的净速率，并与总细胞ATP代谢率进行比较，来检验这种可能性。在未经处理的大鼠的非收缩性肌肉中，CK和AK催化的磷酰转移的净速率分别相当于总ATP代谢率的88%和7%。将这些结果与已报道的对总磷酸肌酸通量的(^{31}P)核磁共振分析结果进行比较，以估计在完整肌肉中，每个产生的磷酸肌酸分子在转运至ATP消耗位点的过程中大约经历50次单向CK催化的磷酰转移。2,4 - 二硝基氟苯对细胞内CK活性进行分级抑制，抑制率高达98%，导致磷酰转移酶催化作用从CK系统逐渐转向AK系统；将增加的AK活性和降低的CK活性相结合，磷酰转移的净速率总和继续接近总细胞ATP代谢率。这些结果表明，在膈肌中，CK和AK作为相互关联的细胞高能磷酰转移系统发挥作用，大多数新生成的ATP在被利用之前通过该系统进行处理。
