The tuftsin retro-inverso analogue H-Thr psi[NHCO](R,S)Lys-Pro-Arg-OH was synthesized through a novel procedure for the high-yield incorporation of isolated retro-inverso bonds into peptide chains and the use of the new Meldrum's acid derivative (CH3)2C(OCO)2CH(CH2)4NHCOCF3 followed by its efficient coupling in solution to trimethylsilylated H-D-Thr(t-Bu)NH2. Closely related peptide impurities were eliminated both from the crude final peptide and the fully protected tetrapeptide amide precursor via ion-exchange and reversed-phase displacement chromatography, respectively. The tuftsin retro-inverso analogue proved to be completely resistant to enzymatic degradation in vitro, either against isolated aminopeptidases or human plasma proteolytic enzymes. When administered either orally or intravenously, it was significantly more active than normal tuftsin in increasing the number of specific antibody secreting cells in spleen of mice immunized with sheep erythrocytes. Furthermore, the analogue exerted an enhanced stimulatory effect on the cytotoxic activity of splenocytes against YAC-1 tumor cells. Finally, retro-inverso-tuftsin was about 10-fold more potent than the native peptide in reducing rat adjuvant arthritis. The resistance of the retro-inverso analogue to peptidases might explain the increased in vivo activities and allows its further immunopharmacological characterization.
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http://dx.doi.org/10.1021/jm00116a005 | DOI Listing |
J Am Chem Soc
January 2025
Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland 4072, Australia.
Transpeptidases are specialized enzymes that have evolved for site-selective modification of peptides and proteins at their backbone termini. Approaches for adapting transpeptidases to catalyze side chain modifications are substantially more restricted, and typically rely on large recognition tags or require specific reaction conditions that are not easily compatible with broader applications. Here we show that the engineered asparaginyl ligase AEP1 catalyzes direct isopeptide ligation by accepting an internal 2,3-diaminopropionic acid (Dap) residue adjacent to Leu, a motif that mimics the canonical N-terminal Gly-Leu substrate.
View Article and Find Full Text PDFBiomed Pharmacother
June 2024
The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3010, Australia; School of Chemistry, University of Melbourne, VIC 3010, Australia. Electronic address:
Molecules
April 2024
Hebei Province Key Laboratory of Research and Development of Traditional Chinese Medicine, Institute of Chinese Mateia Medica, Chengde Medical University, Chengde 067000, China.
Poor selectivity to tumor cells is a major drawback in the clinical application of the antitumor drug doxorubicin (DOX). Peptide-drug conjugates (PDCs) constructed by modifying antitumor drugs with peptide ligands that have high affinity to certain overexpressed receptors in tumor cells are increasingly assessed for their possibility of tumor-selective drug delivery. However, peptide ligands composed of natural L-configuration amino acids have the defects of easy enzymatic degradation and insufficient biological stability.
View Article and Find Full Text PDFBiomolecules
June 2023
Centre of Chemistry, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
Pharmaceutics
May 2023
CNR Neuroscience Institute, Padua Unit, Viale G. Colombo 3, 35131 Padova, Italy.
Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer, and is among the most aggressive and still incurable cancers. Innovative and successful therapeutic strategies are extremely needed. Peptides represent a versatile and promising tool to achieve tumor targeting, thanks to their ability to recognize specific target proteins (over)expressed on the surface of cancer cells.
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