Fractionation and specificity studies on stem bromelain.

The presence, in the juice of pineapples, of a proteolytic enzyme or enzymes under the name of bromelin (2) has long been known, and some of the characteristics of this enzyme have been described (3-7). The ,juice of the stem of the pineapple plant was found by Heinicke and Gortner (8) to contain a similar enzyme. The acetone precipitate from the stem juice, which is called stem bromelain,’ is now available in quantity, and this was used as the starting material in the present investigation. The purpose of the present study was to purify and characterize stem bromelain to such an extent that further investigations could be carried out on the structure of the enzyme and the mechanism of its action. Such an analysis is of particular interest in view of recent studies on crystalline papain (lo), since similarities of the pineapple enzyme to papain have been reported by previous investigators (3-5). Another objective of this investigation was to determine the possible usefulness of this enzyme for studies of the amino acid sequence of peptides and proteins.