For the calibration of the pH-stat;

For the calibration of the pH-stat; the amount of base consumed
during hydrolysis was recorded. The samples of
hydrolysates were taken at timed intervals and l-leucine and
l-serine equivalents were determined by TNBS and OPA reactions,
respectively. After correlation of the base consumption
with l-leucine and l-serine equivalents, slopes (b) of the
straight lines were obtained. Then, the pK values were calculated
from the following equations given by Adler-Nissen