Spectroscopic Characterization of Copper(ii)-Based Tetrapeptides

Abstract

Five different histidine and aspartic acid based tetrapeptides were designed using LOMETS and PyMol. They were chemically synthesized following the solid phase Fmoc-peptide synthesis protocols and were analysed using the reverse-phase High Performance Liquid Chromatography (HPLC) C 18 analytical column for the purity. The peptides were further analysed by Liquid Chromatography Mass Spectrometry (LCMS) to see if the desired peptides were synthesized systematically. Copper(II) acetate monohydrate was bound to the peptides and the best molar ratio for the binding of these metal salts to peptides was 2:1. These observations were monitored through several spectroscopic techniques. The first physical observations for the successful synthesis of metallopeptides were the colour change, the melting/decomposition points and the solubility of these metallopeptides. Due to the visible colour change of the peptides to metallopeptides, UV-Visible spectroscopy and UVFluorescence spectroscopy were used as a qualitative analysis tests and the results were in agreement with other researchers' data from similar researches.Keywords: copper(II), histidine, aspartic acid, tetrapeptides, spectroscopic Abstrak Lima tetrapeptida berbeza yang mempunyai histidine dan asid aspartik direkabentuk oleh LOMETS dan PyMol. Tetrapeptida ini disintesis mengikut skim fasa pepejal peptida dan dianalisis menggunakan fasa sonsang Kromatografi Cecair Berprestasi Tinggi (HPLC) C 18 turus analisis untuk mengetahui keaslian peptida. Kesemua peptida ini dianalisis mengunakan Kromatografi CecairSpektrometer Jisim (LC-MS) untuk mengkaji sintesis peptida secara sistematik. Kuprum(II) asetat monohidrat terikat kepada peptida dan nisbah mol yang terbaik untuk mengikat garam logam ini kepada peptida adalah 2:1. Cerapan ini telah dipantau melalui beberapa teknik spektroskopi. Pemerhatian fizikal pertama untuk logam peptida yang berjaya disintesis ialah perubahan warna, takat lebur/penguraian dan kebolehlarutan peptida logam ini. Oleh kerana perubahan warna yang nyata dalam dari peptida kepada logam peptida, spektroskopi Ultralembayung-tampak (UV-Vis) dan spektroskopi Ultralembayung-Pendafluor (UVFluorescence) digunakan sebagai ujian analisis kuantatif dan data yang diperolehi adalah setara dengan perolehan data bagi penyelidikan yang serupa.Kata kunci: Kuprum(II), histidin, asid aspartik, tetrapeptida, spektroskopi ISSN -2506 Mohd. Basyaruddin et al: SPECTROSCOPIC CHARACTERIZATION OF COPPER(II)-BASED TETRAPEPTIDES 736Introduction Metallopeptides that are easier and cheaper to synthesise when compared to metalloproteins have caught the attention of many researchers. Metallopeptides, synthesized from metal salt and peptides, are known as pseudoproteins. They imitate the applications of large proteins especially in the industrial field of catalysis as well as in biological applications [1]. Metallopeptides are hybrid structures that combine peptides and metal and in this project, the transition metal copper(II) was used, that has various roles when used as b...