Occurrence and evolutionary conservation analysis of α-helical cationic amphiphilic segments in the human proteome.

The existence of encrypted fragments with antimicrobial activity in human proteins has been thoroughly demonstrated in the literature. Recently, algorithms for the large-scale identification of these segments in whole proteomes were developed, and the pervasiveness of this phenomenon was stated. These algorithms typically mine encrypted cationic and amphiphilic segments of proteins, which, when synthesized as individual polypeptide sequences, exert antimicrobial activity by membrane disruption.

Probing human proteins for short encrypted antimicrobial peptides reveals Hs10, a peptide with selective activity for gram-negative bacteria.

Background: Some cationic and amphiphilic α-helical segments of proteins adsorb to prokaryotic membranes when synthesized as individual polypeptide sequences, resulting in broad and potent antimicrobial activity. However, amphiphilicity, a determinant physicochemical property for peptide-membrane interactions, can also be observed in some β-sheets.

Methods: The software Kamal was used to scan the human reference proteome for short (7-11 amino acid residues) cationic and amphiphilic protein segments with the characteristic periodicity of β-sheets.

Intragenic antimicrobial peptides (IAPs) from human proteins with potent antimicrobial and anti-inflammatory activity.

Following the treads of our previous works on the unveiling of bioactive peptides encrypted in plant proteins from diverse species, the present manuscript reports the occurrence of four proof-of-concept intragenic antimicrobial peptides in human proteins, named Hs IAPs. These IAPs were prospected using the software Kamal, synthesized by solid phase chemistry, and had their interactions with model phospholipid vesicles investigated by differential scanning calorimetry and circular dichroism. Their antimicrobial activity against bacteria, yeasts and filamentous fungi was determined, along with their cytotoxicity towards erythrocytes.

Identification and characterization of phospholipases A from the skin secretion of Pithecopus azureus anuran.

The present work reports the isolation, characterization and the complete sequence of a phospholipase A (PLA) present in the skin secretion of Pithecopus azureus. Among several peptides and small proteins previously described by our group from some species belonging to this amphibian genus (formerly named Phyllomedusa), a 15 kDa N-glycosylated protein showing PLA activity was purified, assayed, sequenced and named Pa-PLA. The Pithecopus azureus skin phospholipase A polypeptide chain is composed by 125 amino acid residues linked by seven disulfide bonds and two N-glycosylated sites (N67 and N108).