The effect of Ca2+, Mg2+ ions, cysteine, and benzoic acid on the activity of purified bromelain from pineapple core extract (Ananas comosus [L]. Merr)

Abstract

In this study, bromelain was isolated from pineapple (Ananas comosus [L]. Merr) core. The initial step of purification of bromelain crude enzymes was carried out by fractionation method using ammonium sulfate followed by ion exchange column chromatography. The highest specific activity of bromelain was obtained at ammonium sulfate fraction 20-50% with the value of 170.83 U/mg and give purity level 3.41 folds compared to crude enzyme extract. Further purification using ion exchange chromatography on DEAE Cellulose was able to increase the specific activity of bromelain to 274.7 U/mg with a purity level of 5.48 folds compared to crude enzyme extract. Determination of kinetics parameters of casein hydrolysis using purified bromelain was performed at optimum condition, ie of pH 7.0, temperature 37°C and a substrate concentration of 1%. The Km and Vmax value obtained were 1.03% (w/v) and 0.6685 U/min, respectively. Cysteine, benzoic acid, and metal ions (Ca2+ and Mg2+) can increase proteolytic activity of the purified bromelain. This suggests that this bromelain belongs to cysteine protease class. The highest enzyme activity was found in addition of 0.3 mM calcium ion of 317.69%. While the addition of magnesium metal ions is at 0.4 mM concentration of 282.06%. The highest proteolytic activity in addition of cysteine and benzoic acid compounds was found at 0.4 mM concentrations of 654.30% and 518.43%.