Samples for intracellular pH determination were
collected and prepared as reported previously (2).
31P-NMR spectroscopy was accomplished on a Varian
Unity Plus-300 spectrometer (Palo Alto, USA), operating
at 121.384 MHz. For a typical spectrum 500 scans
were accumulated using 45o pulses with a repetition
time of 0.585 s. Chemical shifts were related to 85 %
H3PO4 (0 ppm) contained in a capillary tube. Condensed
and cooled mycelium was placed in 10 mm NMR tube
and poured with cooled buffered methanol. Finally 10 %
of D2O was added. During the spectroscopy the sample
was kept at (–40.0 0.1) oC by ventilating the sample
with nitrogen pre-cooled on dry ice. Intracellular pH values
were determined from a calibration curve by com