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Abstract: Two bradykinin-related peptides (Protopolybiakinin-I and Protopolybiakinin-II) were isolated from the venom of the social wasp Protopolybia exigua by RP-HPLC, and sequenced by Edman degradation method. Peptide sequences of Protopolybiakinin-I and Protopolybiakinin-II were DKNKKPIRVGGRRPPGFTR-OH and DKNKKPIWMAGFPGFTPIR-OH, respectively. Synthetic peptides with identical sequences to the bradykinin-related peptides and their biological functions were characterized. Protopolybiakinin-I caused less potent constriction of the isolated rat ileum muscles than bradykinin (BK). In addition, it caused degranulation of mast cells which was seven times more potent than BK. This peptide causes algesic effects due to the direct activation of B2-receptors. Protopolybiakinin-II is not an agonist of rat ileum muscle and had no algesic effects. However, Protopolybiakinin-II was found to be 10 times more potent as a mast cell degranulator than BK. The amino acid sequence of Protopolybiakinin-I is the longest among the known wasp kinins. [Copyright &y& Elsevier]

• Characterization of serum degradome profiling in gastric adenocarcinoma (GAC). • Serum levels of 33 peptides of GAC patients and controls differed significantly. • Elevated serum levels of the phosphorylated form of fibrinopeptide A in GAC samples. • Metallo- and Serino-proteases were predicted for activity change in GAC samples. • Correlation of proteolytic processing and peptidome sculpting in GAC physiopathology. We aimed to identify serum level variations in protein-derived peptides between patients diagnosed with gastric adenocarcinoma (GAC) and non-cancer persons (control) to detect the activity changes of proteases and explore the auxiliary diagnostic value in the context of GAC physiopathology. The label-free quantitative peptidome approach was applied to identify variants in serum levels of peptides that can differentiate GAC patients from the control group. Peptide sequences were submitted against Proteasix tool predicting proteases potentially involved in their generation. The activity change of proteases was subsequently estimated based on the peptides with significantly altered relative abundance. In turn, activity change prediction of proteases was correlated with relevant protease expression data from the literature. A total of 191 peptide sequences generated by the cleavage of 36 precursor proteins were identified. Using the label-free quantification approach, 33 peptides were differentially quantified (adjusted fold change ≥ 1.5 and p-value < 0.05) in which 19 were up-regulated and 14 were down-regulated in GAC samples. Of these peptides, fibrinopeptide A was significantly decreased and its phosphorylated form ADpSGEGDFLAEGGGVR was upregulated in GAC samples. Activity change prediction yielded 10 proteases including 6 Matrix Metalloproteinases (MMPs), Thrombin, Plasmin, and kallikreins 4 and 14. Among predicted proteases in our analysis, MMP-7 was presented as a more promising biomarker associated with useful assays of clinical practice for GAC diagnosis. Our experimental results demonstrate that the serum levels of peptides were significantly differentiated in GAC physiopathology. The hypotheses built on protease regulation could be used for further investigations to measure proteases and their activity levels that have been poorly studied for GAC diagnosis. [ABSTRACT FROM AUTHOR]

Protein hydrolyzates of Stripped weakfish (Cynoscion guatucupa) industrial byproducts were prepared, and their antimicrobial and antioxidant activities, as well as bioaccessibility were evaluated. Byproducts were hydrolyzed by Alcalase (HA) and Protamex (HP) to achieve degrees of hydrolysis (DH) of 5, 10 and 15%, respectively. Resulting hydrolyzates were enzymatically digested with pepsin and pancreatin to determine the in vitro bioaccessibility. The highest antimicrobial activity was verified for HA with DH 5% (HA5) against Escherichia coli O157:H7 (5.50 ± 0.17 mm). Whereas HP with DH 5% (HP5) showed the highest antioxidant activity for the tested assays. After simulated in vitro gastrointestinal digestion, all samples were bioaccessible and showed an increase for the ABTS and hydroxyl radical scavenging with the highest activities for HA5 (87.7 ± 0.21%) and HP5 (87.5 ± 0.34%) and HP5 (96.7 ± 0.86%) and HP15 (97.5 ± 0.15%), respectively. We then submitted HA5 and HP5 to peptide sequences analysis, the bioactivities were attributed to the presence of amino acid such Phe, Leu, and Trp in the peptide sequences and peptide sequences like WDDMEK (HP5). The developed peptides present a potential for use as natural antimicrobial and antioxidant preservatives in food. • Hydrolyzates of C. guatucupa byproducts were prepared using Alcalase and Protamex. • Inhibition of E. coli and S. aureus growth by protein hydrolyzates with 5% DH. • Hydrolyzates with 5% DH by Protamex showed higher antioxidant activity. • The hydrolyzates were bioaccessible with antioxidant activity. • Bioactivities were attributed to the presence of specific amino acids or fragments. [ABSTRACT FROM AUTHOR]

[Display omitted] • In vitro gastrointestinal digestion was performed with yam (D. cayennensis) proteins. • Simulated digestion of yam proteins yielded approximately 1000 peptides. • In silico analysis revealed peptide sequences similar to known bioactive peptides. • Yam peptides exhibited antioxidant effect, ACE inhibition and DNA protection. • Low amounts of yam hydrolysates were capable of inhibit Escherichia coli growth. Bioactive peptides have been broadly studied for their contribution to human health. This study aimed to identify bioactive peptides generated by in vitro gastrointestinal digestion of yam proteins. Yam protein concentrate (YPC) was submitted to simulated digestion. Gastric phase hydrolysate (GPH) and total gastrointestinal phase hydrolysate (GIPH) had their peptides identified by nanoLC-ESI-MS/MS. Peptide sequences were subjected to a database-driven (BIOPEP) bioactivity search. In vitro tests included: Antioxidant activity, DNA damage protection, ACE-inhibitory activity and antibacterial activity against the bacteria Escherichia coli , Salmonella sp. and Lysteria monocytogenes. Simulated digestion generated small peptides (mostly MW < 3500 Da), several of them with potential bioactive sequences predicted in silico. In both GPH and GIPH biological activities were detected, although GIPH displayed stronger DNA damage protection and antibacterial activity against Escherichia coli. The digestion of yam proteins releases promising biologically active peptides which can contribute to the prevention of bacterial infection and chronic degenerative diseases, with beneficial effects to human health. [ABSTRACT FROM AUTHOR]