Synthesis of antimicrobial TAT multimers

• Main Author: Chiongson, Justin Brian
• Format: text
• Language: English
• Published: Animo Repository 2019
• Subjects: Peptides > Synthesis; Anti-infective agents; Amino Acids, Peptides, and Proteins; Cells; Medicine and Health Sciences
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/5839
• Institution: De La Salle University

Cell penetrating peptides (CPP) are short cationic peptides that offer therapeutic use as drug cargoes through their innate ability to permeate the cell membrane. The tridecapeptide (GRKKRRQRRRPPQ) is a known sequence from the 86 to 102 amino acid long protein from the human immunodeficiency virus (HIV)-1 TAT at residues 48 to 60. This peptide has been shown to be an effective antibacterial agent (MIC₅₀ at 2-8 Μm) and cellular translocation in the monomer form. Since better bactericidal action and permeation is observed in prior studies of the TAT to tetramer may further enhance the properties of the peptide. Hence, this study aimed to investigate the antimicrobial activity of TAT peptide multimers. Using bis-Fmoc protected lysine allowed for the synthesis of the multimers in a non-linear approach to maximize the efficiency of the synthesis. The monomeric, dimeric, tetrameric TAT peptides were synthesized through solid phase peptide synthesis, purified by reverse phase high performance liquid chromatography and characterized by mass spectrometry. Also, the secondary structure of the multimeric CPPs were investigated using circular dichroism (CD). The far-UV CD spectra of the multimers revealed that all the synthesized CPPs followed a polyproline-II helix. Branched dimerization of TAT using bis-Fmoc protected lysine allowed the TAT units to retain it monomeric identity even upon mutlimerization. The synthesized peptides were also tested for antimicrobial activity against Staphylococcus aureus, Esherichia coli and Staphylococcus saprophyticus using microbroth susceptibility and minimum inhibitory concentration test. All three test pathogens were found to be non-susceptible against the monomeric peptide. However, S. saprophyticus had shown susceptibility with the TAT peptides dimer and tetramer. The MIC₅₀ and MIC₉₀ of the dimer against the susceptible pathogen was 12.50 μM and 6.25 μM, respectively. The tetrameric TAT demonstrated 90% growth inhibition of S. sap