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A Fluorogenic Peptide Cleavage Assay to Screen for Proteolytic Activity: Applications for coronavirus spike protein activation
Published on: January 9, 2019
Structural characterization, cryoprotective potential, and mechanistic insights of thawed drip proteolytic peptides
Xiaoyu Han1, Jinxuan Cao1, Shiqi Liu1
1Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Ministry of Education, 100048 Beijing, China; Beijing Engineering and Technology Research Center of Food Additives, School of Food and Health, Beijing Technology and Business University, 100048 Beijing, China.
Abstract:
This study explored potential of thawed drip proteolytic peptides as cryoprotectants by analyzing structure, thermal hysteresis activity and protection on catalase and Streptococcus thermophilus. The peptides were fractionated into three molecular weight ranges: > 10 kDa, 3-10 kDa and <3kDa. The <3kDa fraction had the highest α-helix and β-sheet contents (41.87% total) as well as superior thermal hysteresis activity (3.47 °C) and catalase residual activity (81.01%), compared to control cryoprotectants (normal saline, sucrose-sorbitol and glycerol). In S. thermophilus, the <3 kDa peptides significantly improved post-freezing survival rates, reaching 97.56% after freezing and 90.89% after freeze-drying. The results showed that the <3 kDa peptides maintained lactate dehydrogenase and β-galactosidase activities in freezing-thawing. Scanning electron microscopy further confirmed intact cell morphology of the S. thermophilus without structural damage. These findings highlighted excellent cryoprotective properties of the <3 kDa peptide fraction, underscoring its potential application in frozen food preservation.
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