Proteolytic characterization of a novel enzymatic extract from Bromelia serra leaves

Abstract

Bromelia serra leaves collected from Corrientes, Argentina, were assessed to analyze and characterize the proteolytic system and to evaluate its potential use as an industrial catalyst. The specific activity of the enzymatic extract (EE), which was prepared using acetone as a precipitating agent of the crude extract (CE), increased 2-3 folds with different substrates (hemoglobin, azocasein and casein). The proteins present in the EE have isoelectric points between 4.55-8.15 and they were significant inhibited by pepstatin A (50%) and E-64 (15%). Proteolytic activity in EE presented high activity in acidic pH (2.7-4), and low activity in neutral alkaline pH (6-11.75). The EE optimum activity was reached at 60ºC, and referring to the thermal stability, it retained over 97% of the proteolytic activity after incubation at a temperature range of 37‒60 ºC for 60 min. The effect of reducing agents and ionic strength were also measured, and it showed that the EE had its maximum activity with 5mM of cysteine, and it was inactivated with 2.5 M of NaCl. The chromatography procedures presented two purified enzymes of 21 and 54 KDa with proteolytic activity. The characteristics of the EE suggest that it is a potential candidate as an industrial catalyst.

Key words
Acidic protease; Bromelia serra leaves; enzymatic extract; size-exclusion chromatography; thermal stability