Brindle K M, Porteous R, Radda G K
Biochim Biophys Acta. 1984 Apr 27;786(1-2):18-24. doi: 10.1016/0167-4838(84)90148-1.
31P-NMR measurements of saturation transfer have been used to measure the exchange of phosphate between phosphocreatine and the gamma-phosphate of ATP in the reaction catalysed by creatine kinase in vitro. The similarity of the calculated exchange flux with the flux estimated from an isotope-exchange experiment, in which exchange of 15N label between creatine and phosphocreatine was measured, showed that the two-site-exchange model, normally used in the analysis of saturation-transfer data, is valid in this case. 15N label exchange was monitored using a heteronuclear 31P/15N spin-echo NMR experiment in which the incorporation of 15N label into phosphocreatine was detected by following the phase modulation of the spin-spin coupled 31P resonance. The isotope-exchange experiment should prove to be useful in studies of creatine kinase in systems where the low concentration of the enzyme precludes saturation-transfer measurements, for example in muscle mitochondria preparations.
利用31P - NMR饱和转移测量法，在体外由肌酸激酶催化的反应中，测量磷酸肌酸与ATP的γ - 磷酸之间的磷酸盐交换。计算得到的交换通量与通过同位素交换实验估算的通量相似，在该同位素交换实验中测量了肌酸和磷酸肌酸之间15N标记的交换，这表明通常用于分析饱和转移数据的双位点交换模型在这种情况下是有效的。使用异核31P/15N自旋回波NMR实验监测15N标记交换，其中通过跟踪自旋 - 自旋耦合的31P共振的相位调制来检测15N标记掺入磷酸肌酸。同位素交换实验在酶浓度低而无法进行饱和转移测量的系统中，例如在肌肉线粒体制剂中，对于肌酸激酶的研究应该是有用的。
