{"id":{"repo_id":"qu-belfast","oai_identifier":"oai:pure.qub.ac.uk/portal:studenttheses/5d3dc262-aa54-4b77-a7bc-e9bed3d96177"},"canonical_url":"https://search.dev.ndltd.org/etd/qu-belfast/oai:pure.qub.ac.uk/portal:studenttheses/5d3dc262-aa54-4b77-a7bc-e9bed3d96177","repository":{"repo_id":"qu-belfast","name":"Queen's University Belfast","base_url":"https://pureadmin.qub.ac.uk/ws/oai"},"display":{"title":"Identification and functional evaluation of a bioactive peptide QUB-2669 from the skin secretion of the American bullfrog Lithobates catesbeiana","abstract":"Due to the prevalence of antimicrobial resistance, researching potential antibiotic substitutes against the multi-drug resistant bacteria has become a global concern. Amphibian skin, secreting many bioactive peptides, is a rich source of novel antimicrobial peptides. In this thesis, QUB-2669, derived from the skin secretion of the American bullfrog, Lithobates catesbeiana, was identified as a member of the ranatuerin-1 family. During the process of peptide synthesis, the methionine residue, containing a sulphur, was accidentally oxidised, therefore, another peptide named MetO-QUB-2669 was obtained. QUB-2669 presented moderate antimicrobial activities against Escherichia coli (minimum inhibitory concentration (MIC) was 32 μM) and Candida albicans (MIC was 64 μM), but was not sensitive against the Gram-positive bacterium Staphylococcus aureus (MIC was 128 μM). Apart from these, QUB-2669 showed slight antiproliferative effects against the cancer cell line NCI H838 at a concentration of 10-4 M. Besides, the haemolytic activity of QUB-2669 was lower than 20 % at the concentration range from 1 μM to 16 μM. Compared with QUB-2669, MetO-QUB-2669 showed lower antimicrobial, antiproliferative and haemolytic activities. Hence, QUB-2669 could be further modified by reducing the haemolytic ability and increasing the antimicrobial activities to become a potential candidate against microbial infections.<br/><br/><i>Thesis embargoed until 31 December 2026</i>.","abstract_html":"Due to the prevalence of antimicrobial resistance, researching potential antibiotic substitutes against the multi-drug resistant bacteria has become a global concern. Amphibian skin, secreting many bioactive peptides, is a rich source of novel antimicrobial peptides. In this thesis, QUB-2669, derived from the skin secretion of the American bullfrog, Lithobates catesbeiana, was identified as a member of the ranatuerin-1 family. During the process of peptide synthesis, the methionine residue, containing a sulphur, was accidentally oxidised, therefore, another peptide named MetO-QUB-2669 was obtained. QUB-2669 presented moderate antimicrobial activities against Escherichia coli (minimum inhibitory concentration (MIC) was 32 μM) and Candida albicans (MIC was 64 μM), but was not sensitive against the Gram-positive bacterium Staphylococcus aureus (MIC was 128 μM). Apart from these, QUB-2669 showed slight antiproliferative effects against the cancer cell line NCI H838 at a concentration of 10-4 M. Besides, the haemolytic activity of QUB-2669 was lower than 20 % at the concentration range from 1 μM to 16 μM. Compared with QUB-2669, MetO-QUB-2669 showed lower antimicrobial, antiproliferative and haemolytic activities. Hence, QUB-2669 could be further modified by reducing the haemolytic ability and increasing the antimicrobial activities to become a potential candidate against microbial infections.&lt;br/&gt;&lt;br/&gt;&lt;i&gt;Thesis embargoed until 31 December 2026&lt;/i&gt;.","abstract_has_math":false,"creators":["Tu, Jingyu"],"institution":"Queen's University Belfast","degree_name":"Master of Philosophy","degree_level":"Masters Thesis","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Zhou, Mei","Wang, Lei","Chen, Tianbao"],"committee_chairs":[],"committee_members":[],"year":2021,"date_issued":"2021-12","date_published":"2021-12","updated_at":"2026-07-24T03:56:04Z","subjects":["Antimicrobial resistance","amphibian skin","bioactive peptides","ranatuerin-1 family","oxidised methionine"],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["oai:pure.qub.ac.uk/portal:studenttheses/5d3dc262-aa54-4b77-a7bc-e9bed3d96177"],"render_values":[{"text":"oai:pure.qub.ac.uk/portal:studenttheses/5d3dc262-aa54-4b77-a7bc-e9bed3d96177","href":null,"code":true}]}]},"links":{"outbound_url":"https://pure.qub.ac.uk/en/studentTheses/5d3dc262-aa54-4b77-a7bc-e9bed3d96177","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Zhou, Mei","Wang, Lei","Chen, Tianbao"]},{"key":"dc:creator","label":"Author","values":["Tu, Jingyu"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2021-12"]},{"key":"dc:date.issued","label":"Date","values":["2021-12"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["School of Pharmacy"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["Queen's University Belfast"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://pure.qub.ac.uk/en/studentTheses/5d3dc262-aa54-4b77-a7bc-e9bed3d96177"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Masters Thesis"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["Master of Philosophy"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Antimicrobial resistance","amphibian skin","bioactive peptides","ranatuerin-1 family","oxidised methionine"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights.embargodate","label":"Dc Rights Embargodate","values":["2026-12-31"]},{"key":"dc:rights.embargoreason","label":"Dc Rights Embargoreason","values":["/dk/atira/pure/core/document/studentthesisembargoreason/publicationissues"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["oai:pure.qub.ac.uk/portal:studenttheses/5d3dc262-aa54-4b77-a7bc-e9bed3d96177","https://pure.qub.ac.uk/en/studentTheses/5d3dc262-aa54-4b77-a7bc-e9bed3d96177"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Due to the prevalence of antimicrobial resistance, researching potential antibiotic substitutes against the multi-drug resistant bacteria has become a global concern. Amphibian skin, secreting many bioactive peptides, is a rich source of novel antimicrobial peptides. In this thesis, QUB-2669, derived from the skin secretion of the American bullfrog, Lithobates catesbeiana, was identified as a member of the ranatuerin-1 family. During the process of peptide synthesis, the methionine residue, containing a sulphur, was accidentally oxidised, therefore, another peptide named MetO-QUB-2669 was obtained. QUB-2669 presented moderate antimicrobial activities against Escherichia coli (minimum inhibitory concentration (MIC) was 32 μM) and Candida albicans (MIC was 64 μM), but was not sensitive against the Gram-positive bacterium Staphylococcus aureus (MIC was 128 μM). Apart from these, QUB-2669 showed slight antiproliferative effects against the cancer cell line NCI H838 at a concentration of 10-4 M. Besides, the haemolytic activity of QUB-2669 was lower than 20 % at the concentration range from 1 μM to 16 μM. Compared with QUB-2669, MetO-QUB-2669 showed lower antimicrobial, antiproliferative and haemolytic activities. Hence, QUB-2669 could be further modified by reducing the haemolytic ability and increasing the antimicrobial activities to become a potential candidate against microbial infections.<br/><br/><i>Thesis embargoed until 31 December 2026</i>."]},{"key":"dc:title","label":"Title","values":["Identification and functional evaluation of a bioactive peptide QUB-2669 from the skin secretion of the American bullfrog Lithobates catesbeiana"]}]}],"canonical_facts":{"dc:contributor.advisor":["Zhou, Mei","Wang, Lei","Chen, Tianbao"],"dc:creator":["Tu, Jingyu"],"dc:date":["2021-12"],"dc:date.issued":["2021-12"],"dc:description.abstract":["Due to the prevalence of antimicrobial resistance, researching potential antibiotic substitutes against the multi-drug resistant bacteria has become a global concern. Amphibian skin, secreting many bioactive peptides, is a rich source of novel antimicrobial peptides. In this thesis, QUB-2669, derived from the skin secretion of the American bullfrog, Lithobates catesbeiana, was identified as a member of the ranatuerin-1 family. During the process of peptide synthesis, the methionine residue, containing a sulphur, was accidentally oxidised, therefore, another peptide named MetO-QUB-2669 was obtained. QUB-2669 presented moderate antimicrobial activities against Escherichia coli (minimum inhibitory concentration (MIC) was 32 μM) and Candida albicans (MIC was 64 μM), but was not sensitive against the Gram-positive bacterium Staphylococcus aureus (MIC was 128 μM). Apart from these, QUB-2669 showed slight antiproliferative effects against the cancer cell line NCI H838 at a concentration of 10-4 M. Besides, the haemolytic activity of QUB-2669 was lower than 20 % at the concentration range from 1 μM to 16 μM. Compared with QUB-2669, MetO-QUB-2669 showed lower antimicrobial, antiproliferative and haemolytic activities. Hence, QUB-2669 could be further modified by reducing the haemolytic ability and increasing the antimicrobial activities to become a potential candidate against microbial infections.<br/><br/><i>Thesis embargoed until 31 December 2026</i>."],"dc:identifier":["oai:pure.qub.ac.uk/portal:studenttheses/5d3dc262-aa54-4b77-a7bc-e9bed3d96177","https://pure.qub.ac.uk/en/studentTheses/5d3dc262-aa54-4b77-a7bc-e9bed3d96177"],"dc:language":["eng"],"dc:publisher.department":["School of Pharmacy"],"dc:publisher.institution":["Queen's University Belfast"],"dc:relation.isreferencedby":["https://pure.qub.ac.uk/en/studentTheses/5d3dc262-aa54-4b77-a7bc-e9bed3d96177"],"dc:rights.embargodate":["2026-12-31"],"dc:rights.embargoreason":["/dk/atira/pure/core/document/studentthesisembargoreason/publicationissues"],"dc:subject":["Antimicrobial resistance","amphibian skin","bioactive peptides","ranatuerin-1 family","oxidised methionine"],"dc:title":["Identification and functional evaluation of a bioactive peptide QUB-2669 from the skin secretion of the American bullfrog Lithobates catesbeiana"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["Masters Thesis"],"dc:type.qualificationname":["Master of Philosophy"]},"updated_at":"2026-07-24T03:56:04Z"}