Lysozyme solution is added to a bufrered suspension
of Sarcina lutea. Aliquots or this reaction mixture are
removed at 5, 10, and 20 minute intervals and transrerred to
colorimeter tubes containing alkali which "rixes" the reaction:
i.e., the alkali stops the action or lysozyme on the
bacterial cells and promotes solution of the cells affected
by lysozyme. The progress of lysis is then determined by
reading the absorbances of the "fixed" aliquots in a photoelectric
colorimeter at 440 ~p. These values are compared
to absorbance standards prepared by similarly tt.fixing" aliquots
of Sarcina that had not been acted on by lysozyme.
The absorbances of the lysed aliquots are calculated as per
cent o.f the mean absorbance of the above standards. These
per cent absorbance values are graphed .for a series of known
lysozyme concentrations. By use of this graph, the activity
of an unknown lysozyme solution can be determined from its
per cent absorbance with an accuracy of *5%-
b. Colorimeter and Tubes