Protein content of the enzymes was determined and this became
the basis for the calculation of specific activities in units of
nmol/mg s1 i.e. nkat/mg of the enzyme protein. The following
procedure was applied to determine the soluble proteins using
photometric determination at 550 nm: 0.5 ml of 10 M NaOH and
3.8 ml of distilled water were pipetted into test tubes. Then
0.2 ml of the sample was added. Test tubes were inserted for
10 min in a boiling water bath and then cooled down to the room
temperature. 0.25 ml of 25% CuSO45H2O solution was added into
tubes, content of the tubes was mixed and then filtered. Absorbance
was measured against the blank by the spectrophotometer
at 550 nm.