{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,24]],"date-time":"2026-10-24T01:17:42Z","timestamp":1792804662554,"version":"4.5.0"},"reference-count":49,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2022,7,20]],"date-time":"2022-07-20T00:00:00Z","timestamp":1658275200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Sheffield Hallam University Vice-Chancellor","id":[{"id":"https:\/\/ror.org\/019wt1929","id-type":"ROR","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Antimicrobial peptides (AMPs) are naturally occurring compounds which possess a rapid killing mechanism and low resistance potential. Consequently, they are being viewed as potential alternatives to traditional antibiotics. One of the major factors limiting further development of AMPs is off-target toxicity. Enhancements to antimicrobial peptides which can maximise antimicrobial activity whilst reducing mammalian cytotoxicity would make these peptides more attractive as future pharmaceuticals. We have previously characterised Smp24, an AMP derived from the venom of the scorpion Scorpio maurus palmatus. This study sought to better understand the relationship between the structure, function and bacterial selectivity of this peptide by performing single amino acid substitutions. The antimicrobial, haemolytic and cytotoxic activity of modified Smp24 peptides was determined. The results of these investigations were compared with the activity of native Smp24 to determine which modifications produced enhanced therapeutic indices. The structure\u2013function relationship of Smp24 was investigated by performing N-terminal, mid-chain and C-terminal amino acid substitutions and determining the effect that they had on the antimicrobial and cytotoxic activity of the peptide. Increased charge at the N-, mid- and C-termini of the peptide resulted in increased antimicrobial activity. Increased hydrophobicity at the N-terminus resulted in reduced haemolysis and cytotoxicity. Reduced antimicrobial, haemolytic and cytotoxic activity was observed by increased hydrophobicity at the mid-chain. Functional improvements have been made to modified peptides when compared with native Smp24, which has produced peptides with enhanced therapeutic indices.<\/jats:p>","DOI":"10.3390\/ijms23147979","type":"journal-article","created":{"date-parts":[[2022,7,20]],"date-time":"2022-07-20T11:22:24Z","timestamp":1658316144000},"page":"7979","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["Improving the Therapeutic Index of Smp24, a Venom-Derived Antimicrobial Peptide: Increased Activity against Gram-Negative Bacteria"],"prefix":"10.3390","volume":"23","author":[{"given":"Kirstie M.","family":"Rawson","sequence":"first","affiliation":[{"name":"Biomolecular Sciences Research Centre, Department of Biosciences and Chemistry, Sheffield Hallam University, Howard Street, Sheffield S1 1WB, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Melissa M.","family":"Lacey","sequence":"additional","affiliation":[{"name":"Biomolecular Sciences Research Centre, Department of Biosciences and Chemistry, Sheffield Hallam University, Howard Street, Sheffield S1 1WB, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peter N.","family":"Strong","sequence":"additional","affiliation":[{"name":"Biomolecular Sciences Research Centre, Department of Biosciences and Chemistry, Sheffield Hallam University, Howard Street, Sheffield S1 1WB, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8633-6952","authenticated-orcid":false,"given":"Keith","family":"Miller","sequence":"additional","affiliation":[{"name":"Biomolecular Sciences Research Centre, Department of Biosciences and Chemistry, Sheffield Hallam University, Howard Street, Sheffield S1 1WB, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,7,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.bcp.2017.03.008","article-title":"The Amazing World of Antibiotics","volume":"133","author":"Demain","year":"2017","journal-title":"Biochem. Pharmacol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1016\/j.tim.2013.12.007","article-title":"Overcoming the Current Deadlock in Antibiotic Research","volume":"22","author":"Hack","year":"2014","journal-title":"Trends Microbiol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1016\/j.bcp.2016.11.017","article-title":"Glycopeptide Resistance: Links with Inorganic Phosphate Metabolism and Cell Envelope Stress","volume":"133","year":"2017","journal-title":"Biochem. Pharmacol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"335","DOI":"10.1016\/j.jcis.2015.09.036","article-title":"Designing Potent Antimicrobial Peptides by Disulphide Linked Dimerization and N-Terminal Lipidation to Increase Antimicrobial Activity and Membrane Perturbation: Structural Insights into Lipopolysaccharide Binding","volume":"461","author":"Datta","year":"2015","journal-title":"J. Colloid Interface Sci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"194","DOI":"10.3389\/fcimb.2016.00194","article-title":"Antimicrobial Peptides: An Emerging Category of Therapeutic Agents","volume":"6","author":"Mahlapuu","year":"2016","journal-title":"Front. Cell. Infect. Microbiol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1128\/AEM.05576-11","article-title":"Bacteriocin Production: A Probiotic Trait?","volume":"78","author":"Dobson","year":"2012","journal-title":"Appl. Environ. Microbiol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"107834","DOI":"10.1016\/j.biotechadv.2021.107834","article-title":"Halocins, Natural Antimicrobials of Archaea: Exotic or Special or Both?","volume":"53","author":"Kumar","year":"2021","journal-title":"Biotechnol. Adv."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"267","DOI":"10.1016\/S0145-305X(99)00010-5","article-title":"Antimicrobial and Cytolytic Polypeptides of Amoeboid Protozoa\u2014Effector Molecules of Primitive Phagocytes","volume":"23","author":"Leippe","year":"1999","journal-title":"Dev. Comp. Immunol."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"L\u00fcbeck, M., and L\u00fcbeck, P.S. (2022). Fungal Cell Factories for Efficient and Sustainable Production of Proteins and Peptides. Microorganisms, 10.","DOI":"10.3390\/microorganisms10040753"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Landi, N., Clemente, A., Pedone, P.V., Ragucci, S., and Di Maro, A. (2022). An Updated Review of Bioactive Peptides from Mushrooms in a Well-Defined Molecular Weight Range. Toxins, 14.","DOI":"10.3390\/toxins14020084"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1186\/s40529-021-00312-x","article-title":"Plant Antimicrobial Peptides: Structures, Functions, and Applications","volume":"62","author":"Li","year":"2021","journal-title":"Bot. Stud."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1337","DOI":"10.1007\/s10529-005-0936-5","article-title":"Human Antimicrobial Peptides: Defensins, Cathelicidins and Histatins","volume":"27","author":"Contreras","year":"2005","journal-title":"Biotechnol. Lett."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1016\/j.toxicon.2014.06.006","article-title":"Antimicrobial Peptides from Scorpion Venoms","volume":"88","author":"Harrison","year":"2014","journal-title":"Toxicon"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"703","DOI":"10.1016\/j.cclet.2016.10.001","article-title":"A Perspective on General Direction and Challenges Facing Antimicrobial Peptides","volume":"28","author":"Zhu","year":"2017","journal-title":"Chin. Chem. Lett."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"491","DOI":"10.1128\/CMR.00056-05","article-title":"Peptide Antimicrobial Agents","volume":"19","author":"Jenssen","year":"2006","journal-title":"Clin. Microbiol. Rev."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"52","DOI":"10.1016\/j.desal.2017.12.003","article-title":"Applications of Nisin for Biofouling Mitigation of Reverse Osmosis Membranes","volume":"429","author":"Jung","year":"2017","journal-title":"Desalination"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1016\/j.toxicon.2013.08.064","article-title":"Venom Proteomic and Venomous Glands Transcriptomic Analysis of the Egyptian Scorpion Scorpio Maurus Palmatus (Arachnida: Scorpionidae)","volume":"74","author":"Possani","year":"2013","journal-title":"Toxicon"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"30","DOI":"10.1016\/j.toxicon.2016.03.014","article-title":"Characterisation of Three Alpha-Helical Antimicrobial Peptides from the Venom of Scorpio Maurus Palmatus","volume":"117","author":"Harrison","year":"2016","journal-title":"Toxicon"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"6146","DOI":"10.1039\/C8SM00707A","article-title":"Visualization of Diffusion Limited Antimicrobial Peptide Attack on Supported Lipid Membranes","volume":"14","author":"Heath","year":"2018","journal-title":"Soft Matter"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Huang, X., Gao, C., Zhao, Q., and Li, C. (2015). Antimicrobial Characterization of Site-Directed Mutagenesis of Porcine Beta Defensin 2. PLoS ONE, 10.","DOI":"10.1371\/journal.pone.0118170"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"10124","DOI":"10.1021\/bi3015086","article-title":"The Lipid Dependence of Antimicrobial Peptide Activity Is an Unreliable Experimental Test for Different Pore Models","volume":"51","author":"Bobone","year":"2012","journal-title":"Biochemistry"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1093\/jac\/48.suppl_1.5","article-title":"Determination of Minimum Inhibitory Concentrations","volume":"48","author":"Andrews","year":"2001","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1042\/bj3590035","article-title":"Characterization of Unique Amphipathic Antimicrobial Peptides from Venom of the Scorpion Pandinus Imperator","volume":"359","author":"Corzo","year":"2001","journal-title":"Biochem. J."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"675","DOI":"10.1016\/j.jaridenv.2004.02.004","article-title":"Lipid Concentrations in Erythrocyte Membranes in Normal, Starved, Dehyrated and Rehydrated Camels (Camelus dromedarius), and in Normal Sheep (Ovis aries) and Goats (Capra hircus) ARTICLE IN PRESS","volume":"59","author":"Mousa","year":"2004","journal-title":"J. Arid Environ."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"366","DOI":"10.3390\/ph7040366","article-title":"\u201cSpecificity Determinants\u201d Improve Therapeutic Indices of Two Antimicrobial Peptides Piscidin 1 and Dermaseptin S4 Against the Gram-Negative Pathogens Acinetobacter Baumannii and Pseudomonas Aeruginosa","volume":"7","author":"Jiang","year":"2014","journal-title":"Pharmaceuticals"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"47","DOI":"10.1007\/s10989-014-9430-z","article-title":"Cationic Antimicrobial Peptides Cytotoxicity on Mammalian Cells: An Analysis Using Therapeutic Index Integrative Concept","volume":"21","author":"Bacalum","year":"2015","journal-title":"Int. J. Pept. Res. Ther."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1290","DOI":"10.1016\/j.ijbiomac.2019.04.013","article-title":"Feasibility of Circular Dichroism to Study Protein Structure at Extreme Concentrations","volume":"132","author":"Li","year":"2019","journal-title":"Int. J. Biol. Macromol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"2385","DOI":"10.1016\/j.bpj.2014.04.020","article-title":"3D Hydrophobic Moment Vectors as a Tool to Characterize the Surface Polarity of Amphiphilic Peptides","volume":"106","author":"Strandberg","year":"2014","journal-title":"Biophys. J."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"379","DOI":"10.1038\/nbt.2572","article-title":"Antimicrobial Peptides Stage a Comeback","volume":"31","author":"Fox","year":"2013","journal-title":"Nat. Biotechnol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"163","DOI":"10.1016\/j.jcis.2018.10.103","article-title":"Membrane Targeting Cationic Antimicrobial Peptides","volume":"537","author":"Ciumac","year":"2019","journal-title":"J. Colloid Interface Sci."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"4","DOI":"10.1002\/1097-0282(2000)55:1<4::AID-BIP30>3.0.CO;2-M","article-title":"Amphipathic, \u03b1-Helical Antimicrobial Peptides","volume":"55","author":"Tossi","year":"2000","journal-title":"Biopolymers"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1692","DOI":"10.1073\/pnas.1215400110","article-title":"Buried Lysine, but Not Arginine, Titrates and Alters Transmembrane Helix Tilt","volume":"110","author":"Gleason","year":"2013","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"3661","DOI":"10.1093\/bioinformatics\/btx495","article-title":"DelPhiForce Web Server: Electrostatic Forces and Energy Calculations and Visualization","volume":"33","author":"Li","year":"2017","journal-title":"Bioinformatics"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"65","DOI":"10.1016\/j.colsurfa.2009.04.018","article-title":"Effects of Single Amino Acid Substitutions on Peptide Interaction with Lipid Membranes and Bacteria\u2013Variants of GKE21, an Internal Sequence from Human LL-37","volume":"354","author":"Ringstad","year":"2010","journal-title":"Colloids Surfaces A Physicochem. Eng. Asp."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Rodr\u00edguez, A., Villegas, E., Montoya-Rosales, A., Rivas-Santiago, B., and Corzo, G. (2014). Characterization of Antibacterial and Hemolytic Activity of Synthetic Pandinin 2 Variants and Their Inhibition against Mycobacterium Tuberculosis. PLoS ONE, 9.","DOI":"10.1371\/journal.pone.0101742"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"2699","DOI":"10.1016\/j.bbamem.2016.07.001","article-title":"Selective Amino Acid Substitution Reduces Cytotoxicity of the Antimicrobial Peptide Mastoparan","volume":"1858","author":"Irazazabal","year":"2016","journal-title":"Biochim. Biophys. Acta-Biomembr."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1007\/s00726-009-0449-y","article-title":"Amino Acid Substitutions in an Alpha-Helical Antimicrobial Arachnid Peptide Affect Its Chemical Properties and Biological Activity towards Pathogenic Bacteria but Improves Its Therapeutic Index","volume":"40","author":"Villegas","year":"2011","journal-title":"Amino Acids"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"13206","DOI":"10.1038\/s41598-020-69995-9","article-title":"Correlation between Hemolytic Activity, Cytotoxicity and Systemic in Vivo Toxicity of Synthetic Antimicrobial Peptides","volume":"10","author":"Greco","year":"2020","journal-title":"Sci. Rep."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"133","DOI":"10.1093\/femsre\/fuv008","article-title":"Bacterial Membrane Lipids: Diversity in Structures and Pathways","volume":"40","author":"Sohlenkamp","year":"2016","journal-title":"FEMS Microbiol. Rev."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"9","DOI":"10.5599\/admet.5.1.375","article-title":"Biomembrane Mimics and Their Roles in Anti-Bacterial Drug Discovery","volume":"5","author":"Hu","year":"2017","journal-title":"ADMET DMPK"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"133","DOI":"10.1016\/j.bpc.2009.11.005","article-title":"Quantifying the Membrane Potential during E. Coli Growth Stages","volume":"146","author":"Bot","year":"2010","journal-title":"Biophys. Chem."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"435","DOI":"10.1111\/j.1348-0421.1979.tb00483.x","article-title":"Lipid Composition of Staphylococcus Aureus and Its Derived L-Forms","volume":"23","author":"Hayami","year":"1979","journal-title":"Microbiol. Immunol."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"6693","DOI":"10.1073\/pnas.79.21.6693","article-title":"Membrane Potential and Gentamicin Uptake in Staphylococcus Aureus","volume":"79","author":"Mates","year":"1982","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Young, S.A., Desbois, A.P., Coote, P.J., and Smith, T.K. (2019). Characterisation of Staphylococcus Aureus Lipids by Nanoelectrospray Ionisation Tandem Mass Spectrometry (NESI-MS\/MS). bioRxiv, 593483.","DOI":"10.1101\/593483"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"1497","DOI":"10.1002\/hep.510240633","article-title":"Transverse Movement of Spin-Labeled Phospholipids in the Plasma Membrane of a Hepatocytic Cell Line (HepG2): Implications for Biliary Lipid Secretion","volume":"24","author":"Pomorski","year":"1996","journal-title":"Hepatology"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"442","DOI":"10.1021\/acsinfecdis.6b00045","article-title":"Contribution of Amphipathicity and Hydrophobicity to the Antimicrobial Activity and Cytotoxicity of \u03b2-Hairpin Peptides","volume":"2","author":"Edwards","year":"2016","journal-title":"ACS Infect. Dis."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"4809","DOI":"10.1128\/AAC.00352-15","article-title":"Altered Competitive Fitness, Antimicrobial Susceptibility, and Cellular Morphology in a Triclosan-Induced Small-Colony Variant of Staphylococcus Aureus","volume":"59","author":"Forbes","year":"2015","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_48","first-page":"4964","article-title":"Phospholipid Composition of the Mammalian Red Cell Membrane Can Be Rationalized by a Superlattice Model","volume":"95","author":"Virtanen","year":"1998","journal-title":"Biophysics"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"W197","DOI":"10.1093\/nar\/gkn238","article-title":"The Jpred 3 Secondary Structure Prediction Server","volume":"36","author":"Cole","year":"2008","journal-title":"Nucleic Acids Res."}],"container-title":["International Journal of Molecular Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1422-0067\/23\/14\/7979\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T23:54:14Z","timestamp":1760140454000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1422-0067\/23\/14\/7979"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,7,20]]},"references-count":49,"journal-issue":{"issue":"14","published-online":{"date-parts":[[2022,7]]}},"alternative-id":["ijms23147979"],"URL":"https:\/\/doi.org\/10.3390\/ijms23147979","relation":{},"ISSN":["1422-0067"],"issn-type":[{"value":"1422-0067","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,7,20]]}}}