Two microassays for determination of a wide range of proteolytic activities using Azocoll as substrate.

Two micromethods for measuring proteolytic activity were developed. A semiquantitative assay on microtitre plates with granular Azocoll as substrate is based on the determination of the time of first appearance of pink colour, t, in the reaction mixture and proteolytic activity is expressed as 1/t. This simple, sensitive and economical method is convenient for preliminary testing of a large number of small samples with unknown proteolytic activity, such as fractions after chromatography. It speeds up considerably proteinase purification. The other test, a quantitative microassay, is a low-cost and time-saving version of the classical method which reduces material consumption and includes automated measurement of absorbance in microtitre plates by a Multiscan reader. Application of these methods are demonstrated.