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Molecular basis for galectin-ligand interactions : Design, synthesis and analysis of ligands

Peterson, Kristoffer LU (2018)
Abstract (Swedish)
I vår kropp finns en myriad av proteiner och celler med viktiga funktioner och de flesta av dem är täckta av kolhydrater. Galektiner är en familj proteiner som har en ficka där olika kolhydrater kan binda in. Genom att kolhydrater på celler eller andra proteiner binder in till denna ficka kan galektiner påverka cellulära funktioner. Vid cancer och inflammation har överproduktion av vissa galektiner observerats, vilket kan vara en indikation på att dessa sjukdomar kan behandlas genom att stoppa bindningen mellan galektiner och proteiner. Detta kan uppnås med hjälp av syntetiska hämmarmolekyler som blockerar den kolhydratbindande fickan hos galektiner.
För att designa en passande hämmarmolekyl behövs information om de molekylära... (More)
I vår kropp finns en myriad av proteiner och celler med viktiga funktioner och de flesta av dem är täckta av kolhydrater. Galektiner är en familj proteiner som har en ficka där olika kolhydrater kan binda in. Genom att kolhydrater på celler eller andra proteiner binder in till denna ficka kan galektiner påverka cellulära funktioner. Vid cancer och inflammation har överproduktion av vissa galektiner observerats, vilket kan vara en indikation på att dessa sjukdomar kan behandlas genom att stoppa bindningen mellan galektiner och proteiner. Detta kan uppnås med hjälp av syntetiska hämmarmolekyler som blockerar den kolhydratbindande fickan hos galektiner.
För att designa en passande hämmarmolekyl behövs information om de molekylära strukturerna i bindningsfickan. Ett sätt att erhålla denna information är att studera kristallstrukturer av naturliga eller syntetiska hämmarmolekyler bundna till galektiner, detta kan sedan användas för att generera idéer till design av mer potenta galektinhämmare. Potenta galektinhämmare kan användas för att studera biologiska processer, biofysikaliska drivkrafter bakom protein-ligand inbindning och fungera som preparat för att diagnostisera och behandla sjukdomar.
I denna avhandling har jag tillverkat hämmarmolekyler för att systematiskt studera och förbättra inbindningen till galektin-1 respektive galektin-3, vilket har resulterat i ett flertal högpotenta och selektiva hämmare. I min jakt på nya högpotenta galektinhämmare utvecklades även en ny syntesmetod för att möjliggöra storskalig syntes av en viktig intermediär molekyl.
Galektin-3 används idag som biomarkör för att diagnostisera hjärtfel men nuvarande metoder med antikroppar kan inte identifiera alla former av galektin-3. Våra utvecklade hämmare binder bra till alla former av galektin-3 så vi har fäst upp en starkt bindande galektinhämmare på en analysplatta som förhoppningsvis kan förbättra nuvarande analysmetoder.
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Abstract
Galectins are a class of β-galactoside-binding proteins that bind glycoconjugates and have been implicated in cancer, regulation of immunity and inflammation. Design and synthesis have achieved highly potent and selective galectin ligands that can inhibit interactions with glycoproteins and have consequent cellular effects. These ligands can be used as tools to further elucidate the roles of galectins in biological processes, and also, potentially, to diagnose and treat diseases. The present theis is about further development of such galectin ligands. A more robust synthetic route to 3-azido-3-deoxy-β-D-galactopyranosides, key intermediates in the synthesis of previous galectin ligands, has been developed.... (More)
Galectins are a class of β-galactoside-binding proteins that bind glycoconjugates and have been implicated in cancer, regulation of immunity and inflammation. Design and synthesis have achieved highly potent and selective galectin ligands that can inhibit interactions with glycoproteins and have consequent cellular effects. These ligands can be used as tools to further elucidate the roles of galectins in biological processes, and also, potentially, to diagnose and treat diseases. The present theis is about further development of such galectin ligands. A more robust synthetic route to 3-azido-3-deoxy-β-D-galactopyranosides, key intermediates in the synthesis of previous galectin ligands, has been developed. Bis-3-(4-aryl-1,2,3-triazol-1-yl)-thiodigalactosides are potent galectin-1 and galectin-3 ligands and by screening different aryl groups, the affinities and selectivities for galectin-1 and galectin-3 were improved. In case of galectin-1, the aryl group binds in a smaller binding pocket than in galectin-3, thus five-membered heterocycles were screened with the 2-thiazole having the highest galectin-1 affinity. In case of galectin-3, substituted phenyls were screened with the 3,4,5-trifluorophenyl having the highest galectin-3 affinity. Introducing these aryl groups onto thiodigalactosides resulted in ligands with single-digit nM affinity and 10-50 fold selectivity towards either of galectin-1 or galectin-3. Structural analysis of the galectin-3 ligands identified orthogonal multipolar fluorine-amide interactions and cation-π interactions as main contributors to the high affinity. Based on these findings, monosaccharide derivatives with high selectivity and low nM galectin-3 affinities were developed. Galectin-3 is a biomarker used to diagnose heart failure and through immobilization of a highly potent galectin-3 ligand in a microtiter plate, an assay has been developed that binds both intact and truncated galectin-3 C-terminal domain. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Grötli, Morten, Department of Chemistry & Molecular Biology, University of Gothenburg, Sweden
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Galectin, Structure-based design, Thiodigalactoside, Huisgen 1,3-dipolar cycloaddition, Protein-ligand binding interactions
pages
148 pages
publisher
Lund University, Faculty of Science, Department of Chemistry, Centre for Analysis and Synthesis
defense location
Lecture hall C, Center for chemistry and chemical engineering, Naturvetarvägen 14, Lund
defense date
2018-03-09 09:30
ISBN
978-91-7422-766-2
978-91-7422-765-5
language
English
LU publication?
yes
id
777b2fa7-2293-453b-9771-0f0ab6f6a6d2
date added to LUP
2018-02-09 13:18:05
date last changed
2018-05-29 12:20:52
@phdthesis{777b2fa7-2293-453b-9771-0f0ab6f6a6d2,
  abstract     = {Galectins are a class of β-galactoside-binding proteins that bind glycoconjugates and have been implicated in cancer, regulation of immunity and inflammation. Design and synthesis have achieved highly potent and selective galectin ligands that can inhibit interactions with glycoproteins and have consequent cellular effects. These ligands can be used as tools to further elucidate the roles of galectins in biological processes, and also, potentially, to diagnose and treat diseases. The present theis is about further development of such galectin ligands. A more robust synthetic route to 3-azido-3-deoxy-β-D-galactopyranosides, key intermediates in the synthesis of previous galectin ligands, has been developed. Bis-3-(4-aryl-1,2,3-triazol-1-yl)-thiodigalactosides are potent galectin-1 and galectin-3 ligands and by screening different aryl groups, the affinities and selectivities for galectin-1 and galectin-3 were improved. In case of galectin-1, the aryl group binds in a smaller binding pocket than in galectin-3, thus five-membered heterocycles were screened with the 2-thiazole having the highest galectin-1 affinity. In case of galectin-3, substituted phenyls were screened with the 3,4,5-trifluorophenyl having the highest galectin-3 affinity. Introducing these aryl groups onto thiodigalactosides resulted in ligands with single-digit nM affinity and 10-50 fold selectivity towards either of galectin-1 or galectin-3. Structural analysis of the galectin-3 ligands identified orthogonal multipolar fluorine-amide interactions and cation-π interactions as main contributors to the high affinity. Based on these findings, monosaccharide derivatives with high selectivity and low nM galectin-3 affinities were developed. Galectin-3 is a biomarker used to diagnose heart failure and through immobilization of a highly potent galectin-3 ligand in a microtiter plate, an assay has been developed that binds both intact and truncated galectin-3 C-terminal domain.},
  author       = {Peterson, Kristoffer},
  isbn         = {978-91-7422-766-2},
  keyword      = {Galectin,Structure-based design,Thiodigalactoside,Huisgen 1,3-dipolar cycloaddition,Protein-ligand binding interactions},
  language     = {eng},
  pages        = {148},
  publisher    = {Lund University, Faculty of Science, Department of Chemistry, Centre for Analysis and Synthesis},
  school       = {Lund University},
  title        = {Molecular basis for galectin-ligand interactions : Design, synthesis and analysis of ligands},
  year         = {2018},
}