Purification, Characterization, and Application for Preparation of Antioxidant Peptides of Extracellular Protease from Pseudoalteromonas sp. H2

The study reported on the isolation of a metalloprotease named EH2 from Pseudoalteromonas sp. H2. EH2 maintained more than 80% activity over a wide pH range of 5-10, and the stability was also nearly independent of pH. Over 65% activity was detected at a wide temperature range of 20-70 degrees C. The high stability of the protease in the presence of different surfactants and oxidizing agents was also observed. Moreover, we also investigated the antioxidant activities of the hydrolysates generated from porcine and salmon skin collagen by EH2. The results showed that salmon skin collagen hydrolysates demonstrated higher DPPH (1,1-diphenyl-2-picrylhydrazyl) (42.88% +/- 1.85) and hydroxyl radical (61.83% +/- 3.05) scavenging activity than porcine skin collagen. For oxygen radical absorbance capacity, the hydrolysates from porcine skin collagen had higher efficiency (7.72 +/- 0.13 mu molTE/mu mol). Even 1 nM mixed peptides could effectively reduce the levels of intracellular reactive oxygen species. The two types of substrates exerted the best antioxidant activity when hydrolyzed for 3 h. The hydrolysis time and type of substrate exerted important effects on the antioxidant properties of hydrolysates. The hydrolyzed peptides from meat collagens by proteases have good antioxidant activity, which may have implications for the potential application of marine proteases in the biocatalysis industry.