Differences in Substrate Specificities for Cysteine Proteinases Used in Blood Group Serology, and the Use of Bromelain in a Two-Phase Inhibitor Technique

Abstract

Because substrate specificities differ between proteolytic enzymes and because knowledge of the optimal enzyme activity levels is necessary in order to standardize procedures used in antibody screening, a study was made of the best common assay method for the routinely employed enzymes bromelain, papain and ficin. Casein degradation was found better suited to this purpose than azoalbumin. With standardization achieved, a useful two-phase bromelain inhibitor technique was devised using bromelain at 20 casein units of activity. This method improved upon the one-stage bromelain technique in terms of sensitivity, freedom from false positive reactions and it compared well with the two-phase papain inhibitor technique.