A comparative study of papain and bromelain in enzymatic oligomerization of l-Phe methyl ester in aqueous environment

Abstract

In this study, we developed an efficient approach for hydrophobic amino acids polymerization in aqueous solution. We compared the catalysis efficiency of papain and bromelain in catalyzing l-phenylalanine methyl ester (l-Phe-Me) for oligomer peptides synthesis. A set of reaction conditions (such as protease type, reaction temperature, time, and pH) have been tested for the polymerization reaction with papain and bromelain, respectively. Moreover, the resultant oligomers were analyzed through ¹HNMR and MALDI-TOF. The results indicated that the average degree of polymerization (DP) reached the highest value (6.74) when papain was used for l-Phe-Me polymerization in phosphate buffer (0.2 M, pH 8) at 40 °C for three hours. At 50 °C, the DP reached 6.62 with a yield of 72.9% when papain as the catalyst. Its yield and DP were 4.50 and 1.27 folds higher than those of the oligo- peptides synthesized by bromelain. Moreover, we found the DP and the yield of oligo(l-Phe) can be enhanced with higher reaction temperature and longer reaction time. In summary, papain presents better catalytic properties compared with bromelain for l-Phe polymerization in terms of DP and yield. Oligomerization catalyzed by papain at high temperature presents a potent procedure for the synthesis of biologically active oligo(l-Phe) peptides.