Abstract
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 °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 μmol·TE/μmol). 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.
Highlights
Proteases are enzymes that hydrolyze peptide bonds of proteins [1]
Our results suggested that salmon skin collagen hydrolysates contained more electron donors, which could react with free radicals, convert them to more stable products, and terminate the radical chain reaction, when compared with porcine skin collagen hydrolysates
The study presented a report on the isolation of a metalloprotease from Pseudoalteromonas sp
Summary
Proteases are enzymes that hydrolyze peptide bonds of proteins [1]. They are the most important and commonly used enzymes in industry, contributing approximately 60% of the total market of industrial enzymes [2], which includes detergents [2], anti-biofilm agents [3], and feather processing, feed processing, wastewater treatment, and food processing enzymes [4]. Chen et al demonstrated that serine protease secreted by Pseudoalteromonas can effectively degrade collagen to prepare antioxidant peptides [8]. The application of metalloproteinases secreted by Pseudoalteromonas is uncommon, especially in the preparation of antioxidant peptides. Many studies have reported that enzymatic hydrolysis of collagen is an effective way to obtain antioxidant peptides [11,12]. There are few reports on noncommercially resistant organic solvent alkaline proteases for antioxidant peptide preparation. It is of great significance to search and prepare proteases that are stable and active under multiple extreme conditions, such as alkaline pH, high salt concentration, wide temperature ranges, and organic solvent. The potential application of the protease to hydrolyze low-value protein resources to prepare antioxidant peptides was explored. This study may have implications for the potential application of marine proteases in the biocatalysis industry
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