1. Backbone cleavages of [M - H](-) anions derived from caerin 1 peptides and some synthetic modifications. Molecular recognition initiating internal cyclisation of Glu23
Craig S Brinkworth, John H Bowie Rapid Commun Mass Spectrom. 2002;16(14):1339-51. doi: 10.1002/rcm.719.
The collision induced spectra of [M - H](-) anions from of caerin 1 peptides and some synthetic modifications show the usual alpha, beta and beta' backbone cleavages together with Ser (epsilon,gamma) and Glu (gamma) cleavages which break the peptide backbone in the vicinity of those residues. All of these cleavages require the peptide backbone to be flexible. There is also a backbone cleavage of a type not observed before. This cleavage involves nucleophilic attack of the carboxylate anion of the Glu23 side chain at the backbone CH of Ile 21. We propose that this cleavage requires the caerin peptide to be in an alpha helical conformation (the 3D structure that this peptide adopts in solution) in order that the interacting groups are held in close proximity.
2. Caerin 1 Peptides, the Potential Jack-of-All-Trades for the Multiple Antibiotic-Resistant Bacterial Infection Treatment and Cancer Immunotherapy
Liyin Xiao, et al. Biomed Res Int. 2022 Apr 11;2022:7841219. doi: 10.1155/2022/7841219. eCollection 2022.
Antibiotic resistance-related bacterial infections and cancers become huge challenges in human health in the 21st century. A number of naturally derived antimicrobial peptides possess multiple functions in host defense, including anti-infective and anticancer activities. One of which is known as the caerin 1 family peptides. The microbicidal properties of these peptides have been long discussed. The recent studies also established the usage of two members in this family, caerin 1.1 and caerin 1.9, in antimultiple antibiotic-resistant bacteria species. It is increasingly evident that caerin 1.1 and caerin 1.9 also contain additional activities in the suppression of tumor. In this review, we briefly outline the therapeutic potentials and possible mechanism of action of caerin 1.1 and 1.9 in the treatment of multiple antibiotic-resistant bacterial infection and cancer immunotherapy.
3. Iodine-125 labeled Australian frog tree host-defense peptides caerin 1.1 and 1.9 better inhibit human breast cancer cells growth than the unlabeled peptides. 125I-caerin 1.9 may better be used for the treatment of breast cancer
Jianwei Yuan, Xinchao You, Guoying Ni, Tianfang Wang, Shelley Cavezza, Xuan Pan, Xiaosong Liu Hell J Nucl Med. 2018 May-Aug;21(2):115-120. doi: 10.1967/s002449910803. Epub 2018 Jul 12.
Objective: We recently showed that host defense caerin peptides isolated from Australian frog tree were able to inhibit cervical cancer tumour cell growth in vitro. We wished to determine if radioactive isotope iodine-125 (125I) can be labeled to caerin 1.9 peptide and if this peptide is bioactive for breast cancer cells treatment. Subjects and methods: The biological function of caerin (1.1 and 1.9) peptides were investigated by in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay. The anti-cancer effect of 125I labeled caerin 1.9 was compared with unlabeled caerin 1.9 peptide. The tissue distribution of 125I labeled caerin 1.9 peptide was further studied in mice. Results: In the current paper, we demonstrated that caerin peptides (1.1 and 1.9) were separately able to inhibit the viability of two breast cancer cell lines in vitro and this inhibition was more profound when these peptides were simultaneously applied. Moreover, 125I can be stably attached to caerin 1.9 peptide with high efficiency. Iodine-125 labeled caerin 1.9 inhibited breast cancer cells line MCF-7 viability more efficiently than free 125I and also than unlabeled caerin 1.9. Additionally, iodine-125 labeled caerin 1.9 in vivo imaging demonstrated that although slightly, it could be accumulated in tumor tissue. Conclusion: Our results from this totally original study indicated that radioactive isotope 125I labeled to caerin peptide 1.9 may be used to treat breast cancer while at the same time the response to treatment may be monitored by simultaneous imaging.
