Phosphoarginine-adenosine triphosphate exchange detected in vivo in a microscopic nematode parasite by flow 31P FT-NMR spectroscopy.

In vivo flow 31P NMR spectroscopy of a microscopic nematode, Steinernema carpocapsae, is described. Long-term viability was maintained during analysis by continuous circulation of an oxygenated suspension of the parasite through an NMR spectrometer. Saturation transfer and inversion recovery were employed under flowing conditions to investigate the kinetics of phosphoarginine<-->adenosine triphosphate exchange. The kinetic constants for the forward and reverse reactions were 0.37/s and 1.45/s, respectively. This report is the first to demonstrate a functional phosphagen kinase in the metabolism of a parasitic helminth.