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.

Background: Proteases constitute the largest product segment in the global industrial enzymes market; they are used in food, pharmaceutical, leather, textile, wood and detergent industries. Alkaline proteases improve the cleaning efficiency of detergents and represent one of the most successful applications of modern industrial biotechnology. The aim of this work was to study the performance of two alkaline phytoproteases, araujiain (Araujia hortorum Fourn.) and asclepain (Asclepias curassavica L.), for their potential application as additive in laundry detergent formulations. Results: The effect of pure non-ionic and ionic surfactants on proteolytic activity of araujiain and asclepain was analyzed measuring the remaining activity after 1 hr of incubation of those enzymes in aqueous solutions of surfactants at different concentrations (0.1, 0.4 and 1% v/v) and temperatures (25, 40 and 60ºC). Besides, the compatibility of the enzymes with six commercial laundry detergents was also studied measuring the remaining proteolytic activity at 37ºC after 1 hr. Commercial detergent components influenced in different ways on araujiain and asclepain, in spite of the similar behaviour of the two enzymes in buffer. In commercial detergent solutions, araujiain expressed between 60% and 140% of its remaining proteolytic activity in buffer (pH 8.5) at 37ºC after 1 hr, while asclepain, was practically inactivate in most of them at the same conditions. Conclusions: Proteolytic extract of Araujia hortorum fulfilled all the requirements for its application as additive for laundry detergents: high stability in a broad temperature range (25-70ºC), high activity in alkaline pH (7.5-9.5) and very good compatibility with the commercial detergent additives. Nevertheless, in spite of its high stability and activity in buffer, the proteolytic extract of Asclepias curassavica did not show the same performance than araujiain.