Abstract
A novel protease JQ-2 produced by Bacillus subtilis JQ-2, was purified and identified to be a peptidase M28 family alkaline metalloprotease with optimum pH and temperature of 11.0 and 52 °C, respectively. SDS-PAGE revealed high proteolytic activity of JQ-2 for κ-casein, and the cleavage site was identified to be at Lys111–Lys112. Ultrafiltration of the casein hydrolysate resulted in U1 fraction (>3 kDa) with good α-glucosidase inhibition ability and U2 fraction (<3 kDa) with good DPPH radical scavenging ability. Identification of the U2 fraction by mass spectrometry revealed three potential new bioactive peptides SLPQNIPP, GLPQEVLN and AVPYPQRDMPIQAF, which were verified by chemical synthesis. Among them, AVPYPQRDMPIQAF had the strongest DPPH radical scavenging ability and α-glucosidase inhibitory activity. The present study demonstrated a novel microbial protease capable of hydrolysing casein to produce new bioactive peptides with potential application in functional dairy products.
Published Version
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