Studies of potential plant parts of Kesinai (Streblus asper) for protease production

Abstract

A study was carried out to study the potential plant parts of Kesinai (Streblus asper) for protease production. The potential parts of Streblus asper such as leaves, stem barks, and twigs were collected and used as a source for extracting protease enzyme. The enzyme was extracted by using phosphate buffer and distilled water at pH 7. The crude enzyme extract was tested for protease assay and casein was used as a substrate. The absorbance of crude enzyme was detected by using GENESYSTM 20 spectrophotometer at 660 nm since the released of tyrosine developed a blue coloration. The protease activity can be calculated from the absorbance by compared with calibration curve. The protease activity of twigs was the highest among the three potential parts. The protease assay for twigs, leaves, and stem barks by using phosphate buffer extraction give the enzyme activity of 0.7976 unit/mL, 0.6475 unit/mL and 0.5261 unit/mL respectively. However, the protease assay for leaves, stem barks and twigs for distilled water extraction shown lower activity compared to phosphate buffer extraction. The activity for twigs, leaves and stem barks by using distilled water extraction was 0.2848 unit/mL, 0.3781 unit/mL and 0.2318 unit/mL respectively. The kinetics study of twigs had been determined by differentiate the concentration of the substrate starting from 0.125 g/L to 1 g/L. From this kinetics studied, it was found that the crude enzyme was obeyed the Michealis-Menten kinetics and the Michealis-Menten’s constant (KM) and maximum attainable velocity (VMax) had been determined. The KM of the protease was 0.0772 g/L while the VMax was 0.3839 unit/mL. This shows that the enzyme exhibited considerable proteolytic activity on casein. Due to the large growth of Streblus asper in Malaysia, it can be potential alternatives for protease production in future investment.