Structure and Function of Stem Bromelain

Abstract

This chapter discusses individual differences among papain, ficin, and stem Bromelain. Bromelain enzymes are proteolytic enzymes found in tissues of pineapple plant and other species of family Bromeliaceae. Stem bromelain is a sulfhydryl protease of plant origin and it resembles papain and ficin. Unlike papain, ficin, or chymopapain, stem bromelain is a glycoprotein. Bromelain has four methionine residues, while papain is known to be devoid of methionine. In connection with some differences in protein structure and in catalytic function of stem bromelain from papain and ficin, it must be pertinent to point out that the pineapple plant belongs to Monocotyledonae, whereas the papaya and fig belong to Dicotyledonae. Stem bromelain favors a basic amino acid ester like BAEE, but it can also hydrolyze at an appreciable rate benzoylglycine ester. In the case of papain, benzoylglycine amide is hydrolyzed only at one-hundredth of the rate for benzoylarginine amide. One may say that stem bromelain has broad substrate specificity. Papain and ficin are also said to have broad specificities. However, bromelain does not so closely resemble papain as papain resembles ficin.