Isolation and sequence analysis of peptides from the skin secretion of the Middle East tree frog Hyla savignyi

In Vitro & In Vivo Studies on Identifying and Designing Temporin-1CEh from the Skin Secretion of Rana chensinensis as the Optimised Antibacterial Prototype Drug

Amphibian skin secretion is an ideal source of antimicrobial peptides that are difficult to induce drug resistance to due to their membrane-targeting mechanism as a new treatment scheme. In this study, a natural antimicrobial peptide Temporin-1CEh was identified by molecular cloning and mass spectrometry from the skin secretions of the Chinese forest frog (Rana chensinensis). Through the study of the structure and biological activity, it was found that Temporin-1CEh was a helical peptide from the Temporin family, and possessed good anti-Gram-positive bacteria activity through the mechanism of membrane destruction. Seven analogues were further designed to obtain broad-spectrum antimicrobial activity and higher stability in different physiological conditions. The results showed that T1CEh-KKPWW showed potent antibacterial activity with significantly increasing the activity against Gram-negative bacteria in vitro and in vivo with low haemolysis. In addition, T1CEh-KKPWW2 showed high sensitivity to the pH, serum or salts conditions, which applied a branched structure to allow the active units of the peptide to accumulate. Even though the haemolytic activity was increased, the stable antibacterial activity made this novel analogue meet the conditions to become a potential candidate in future antimicrobial and antibiofilm applications.

FT-MS in the de novo top-down sequencing of natural nontryptic peptides

The present review covers available results on the application of FT-MS for the de novo sequencing of natural peptides of various animals: cones, bees, snakes, amphibians, scorpions, and so forth. As these peptides are usually bioactive, the animals efficiently use them as a weapon against microorganisms or higher animals including predators. These peptides represent definite interest as drugs of future generations since the mechanism of their activity is completely different in comparison with that of the modern antibiotics. Utilization of those peptides as antibiotics can eliminate the problem of the bacterial resistance development. Sequence elucidation of these bioactive peptides becomes even more challenging when the species genome is not available and little is known about the protein origin and other properties of those peptides in the study. De novo sequencing may be the only option to obtain sequence information. The benefits of FT-MS for the top-down peptide sequencing, the general approaches of the de novxxo sequencing, the difficult cases involving sequence coverage, isobaric and isomeric amino acids, cyclization of short peptides, the presence of posttranslational modifications will be discussed in the review.

Screening & analysis of anionic peptides from Foeniculum vulgare Mill by mass spectroscopy

Fennel (Foeniculum vulgare Mill.) member from the family Umbelliferae (Apiaceae) and has been used in Saudi Arabia as an medicine as of the from the tradition. Our previous work with seed extracts of this plant generated DEAE-ion exchange purified proteins that exhibited antibacterial properties. The current study moves this work forward by using 2-D gel separation and MALDI TOF/TOF to identify proteins in this active extract. Fourteen protein spots were excised, digested, and identified. Several putative functions were identified, including: a copper-trans locating ATPase PAA1 chloroplastic-like isoform X1; a cytosolic enolase; a putative pentatricopeptide repeat-containing protein; an NADP-requiring isocitrate dehydrogenase; two proteins annotated as being encoded downstream from Son-like proteins; three probable nuclear proteins 5–1; and four predicted/ unidentified proteins. Future efforts will further characterize their relevant antimicrobial properties with the aim of cloning and high throughput synthesis of the antimicrobial element(s).