Figure 3

³¹P saturation transfer NMR spectra of untreated Rana Pipiens follicles. Arrows indicate where saturation was alternately applied. Upper spectra (A): ³¹P NMR showing saturation transfer from γP → PCr. The control spectrum with saturating RF placed off-resonance (upper trace), the spectrum with γP resonance saturated (middle trace) and the difference spectrum (lower trace) are compared. Lower spectra (B): ³¹P NMR saturation transfer results for PCr → γP. The control spectrum (a), the spectrum with PCr saturated (b), and the difference spectrum (a - b). Each spectrum was obtained with a selective low power RF pulse of 5 sec duration placed in the labeled (arrow) position, followed by a 90° nonselective observation pulse and a 0.8 sec acquisition time. A total of 1000 transients were collected at 20°C for each spectrum by alternating the saturating RF between an off resonance and the γP (or PCr) peak positions after each block of 100 transients, as described in the text. A line-broadening of 100 Hz was applied to each spectrum. The large peaks in the difference spectra are due to incomplete cancellation of the overwhelming phosvitin signal.