FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W70074847> ?p ?o ?g. }

• W70074847 abstract "Naturally occurring cyclic peptides have been discovered in all kingdoms of life (i.e. plant, animal, fungi and bacteria). They are extremely stable and have important roles as defense molecules for their host organisms. Momordica cochinchinensis trypsin inhibitor II, MCoTI-II, is a naturally occurring cyclic peptide present in the seeds of the tropical fruit Momordica cochinchinensis; it is an extremely potent trypsin inhibitor with sub-nanomolar activity and belongs to the family of cyclic plant peptides called cyclotides. Recent studies have shown that MCoTI-II can penetrate cells and has potential as a stable grafting scaffold for the design of novel peptide drug leads. This study has focussed on determining the potential of MCoTI-II as a scaffold for the design of novel leads for the treatment of chronic myeloid leukaemia (CML). CML is a blood cancer, induced by a genetic translocation between chromosome 9 and 22, this translocation produces the oncogenic enzyme Bcr-Abl, a tyrosine kinase expressed in the cytoplasm of CML cells. Bcr-Abl can be inhibited by small molecules targeting the ATP binding site. However, mutations in the catalytic domain present a therapeutic challenge and new drugs are in development to overcome current drug resistance from the frontline drugs (i.e. imatinib, nilotinib and dasatinib). This thesis is concerned with a novel approach to developing such drugs based on peptides. Chapter 1 introduces cyclic peptides and explains how they can be exploited in drug design. It particularly focuses on MCoTI-II and the most recent studies of this potent peptide as a drug scaffold. Chapter 1 also gives an overview of CML, its treatment and treatment challenges. The aim of Chapters 2 and 3 was to gain a better understanding of the structure activity relationships of MCoTI-II, focussing on the role of the cyclic backbone, and its potential in drug development. In Chapter 2 an NMR relaxation study of MCoTI-II was undertaken to clarify which regions of the molecule are the most flexible. The relaxation study showed that MCoTI-II is a rigid molecule with the highest flexibility in loop 6, which is also the point of cyclization. The interaction between MCoTI-II and its native target, trypsin, was studied using X-ray crystallography, NMR and HPLC at the optimal pH for trypsin (~7-8). These studies showed that the cyclic backbone is vital for the high potency of MCoTI-II, but also that trypsin slowly cleaves MCoTI-II over a timeframe of several days. In Chapter 3 the interaction between MCoTI-II and trypsin was studied over a wide range of pH values (1.7-12) using HPLC, LC-MS and NMR spectroscopy. These studies showed that trypsin cleaves MCoTI-II in a pH dependent matter, and that the rate of hydrolysis also is pH dependent. It also highlighted that the cyclic backbone is vital for the high potency of MCoTI-II even though cyclization does not create a stronger interaction between MCoTI-II and trypsin compared to other trypsin inhibitors from the same plant family. The importance of the cyclic backbone was confirmed by comparing MCoTI-II with four linear mutants all open in loop 6. Lastly the three-dimensional structure of MCoTI-II cleaved by trypsin was solved. This is the first structure of a cyclotide interacting with its native target and provided insights into the molecular details of the interaction. The aim of Chapter 4 was to investigate the cell penetration properties of MCoTI-II without recourse to external chemical labelling, which has been used in all previous cell-based studies on this peptide. Hence, an in cell-NMR study was set up whereby the seven glycine residues of MCoTI-II were non-invasively isotope labelled with 15N. The [15N-Gly]-MCoTI-II was incubated with the human cell-lines RAW, MCF-7 and HEK. The in-cell NMR study of MCoTI-II confirmed that MCoTI-II is intrinsically a cell penetrating peptide, and the cell penetration is not induced by chemical tagging such as the fluorescence dye Alexa used in previous studies. Chapter 5 focused on the development of an Abl kinase activity assay for the assessment of CML lead peptide activity. Two analytical methods were used, LCMS and flow cytometry, and both methods were shown to be capable of detecting and quantifying Abl kinase activity and inhibition by the detection of Abl substrate phosphorylation. However the flow cytometry Abl activity assay was found to be the most reliable. In Chapter 6 novel CML lead peptides were designed, synthesised and assayed for activity in the flow cytometry Abl activity assay. Two target sites, site 1 and site 2 were investigated for inhibition of Abl substrate phosphorylation. A peptide designed to target site 1 (the Abl activation loop binding site for active Abl) showed inhibition of Abl substrate phosphorylation, and several potential novel substrates interacted with site 2 (the Abl substrate binding site). In summary, the studies presented in this thesis have given important insights about the physio-chemical properties of MCoTI-II and how these can be exploited in drug design. The thesis also presents a novel and efficient Abl activity assay, which importantly does not rely on radioactive labelling. Lastly this project has contributed to the identification of a novel target site of the CML oncogenic enzyme Abl and established that peptides, stabilised by the cyclic peptide scaffold MCoTI-II, can interact with Abl." @default.
• W70074847 created "2016-06-24" @default.
• W70074847 creator A5090196642 @default.
• W70074847 date "2012-01-01" @default.
• W70074847 modified "2023-09-27" @default.
• W70074847 title "MCoTI-II and Chronic Myeloid Leukaemia Cyclic Peptides as Therapeutic Leads in the Treatment of CML" @default.
• W70074847 hasPublicationYear "2012" @default.
• W70074847 type Work @default.
• W70074847 sameAs 70074847 @default.
• W70074847 citedByCount "0" @default.
• W70074847 crossrefType "journal-article" @default.
• W70074847 hasAuthorship W70074847A5090196642 @default.
• W70074847 hasConcept C185592680 @default.
• W70074847 hasConcept C2777413986 @default.
• W70074847 hasConcept C2777583451 @default.
• W70074847 hasConcept C2778729363 @default.
• W70074847 hasConcept C2779536868 @default.
• W70074847 hasConcept C42362537 @default.
• W70074847 hasConcept C502942594 @default.
• W70074847 hasConcept C55493867 @default.
• W70074847 hasConcept C62478195 @default.
• W70074847 hasConcept C86803240 @default.
• W70074847 hasConcept C98274493 @default.
• W70074847 hasConceptScore W70074847C185592680 @default.
• W70074847 hasConceptScore W70074847C2777413986 @default.
• W70074847 hasConceptScore W70074847C2777583451 @default.
• W70074847 hasConceptScore W70074847C2778729363 @default.
• W70074847 hasConceptScore W70074847C2779536868 @default.
• W70074847 hasConceptScore W70074847C42362537 @default.
• W70074847 hasConceptScore W70074847C502942594 @default.
• W70074847 hasConceptScore W70074847C55493867 @default.
• W70074847 hasConceptScore W70074847C62478195 @default.
• W70074847 hasConceptScore W70074847C86803240 @default.
• W70074847 hasConceptScore W70074847C98274493 @default.
• W70074847 hasLocation W700748471 @default.
• W70074847 hasOpenAccess W70074847 @default.
• W70074847 hasPrimaryLocation W700748471 @default.
• W70074847 hasRelatedWork W167459 @default.
• W70074847 hasRelatedWork W1993695450 @default.
• W70074847 hasRelatedWork W1994315214 @default.
• W70074847 hasRelatedWork W2008744080 @default.
• W70074847 hasRelatedWork W2021350823 @default.
• W70074847 hasRelatedWork W2031131085 @default.
• W70074847 hasRelatedWork W2044960732 @default.
• W70074847 hasRelatedWork W2082927837 @default.
• W70074847 hasRelatedWork W2084336971 @default.
• W70074847 hasRelatedWork W2150766579 @default.
• W70074847 hasRelatedWork W2162570875 @default.
• W70074847 hasRelatedWork W2203622647 @default.
• W70074847 hasRelatedWork W2289856430 @default.
• W70074847 hasRelatedWork W2606115399 @default.
• W70074847 hasRelatedWork W2765498925 @default.
• W70074847 hasRelatedWork W2893890930 @default.
• W70074847 hasRelatedWork W2947842456 @default.
• W70074847 hasRelatedWork W3184728709 @default.
• W70074847 hasRelatedWork W33793218 @default.
• W70074847 hasRelatedWork W2741750908 @default.
• W70074847 isParatext "false" @default.
• W70074847 isRetracted "false" @default.
• W70074847 magId "70074847" @default.
• W70074847 workType "article" @default.