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Dependence on pH of Structural and Dynamical Changes of a Calmodulin Domain Mutant
Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
2015 (English)Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
Abstract [en]

Calmodulin (CaM) is a highly conserved protein able to bind Ca2+. When Ca2+ is bound the protein can bind and activate further proteins with several individual functions. CaM switches to a more open conformation when Ca2+-bound and is able to do so at a high rate. Little is known about the conformational switches between apo and Ca2+-bound states. A hypothesis suggests that protonation/deprotonation of a histidine side-chain is part of the answer and thus the dynamics of CaM would be pH dependent. This was further investigated in this thesis. Methods to carry out the project included protein expression of isotope labelled CaM-TR2C E140Q, standard protein purification and protein adapted Nuclear Magnetic Resonance (NMR) spectroscopy. The results suggest that CaM-TR2C E140Q is likely to depend on pH and that histidine 107 (H107) may have a central role in the conformational changes observed. At lower pH it was also suggested that CaM-TR2C E140Q obtained a more open conformation with weakened intramolecular interactions and that the tertiary structure of CaM-TR2C E140Q may have been disrupted.

Abstract [sv]

Calmodulin (CaM) är ett, till hög grad konserverat protein med möjlighet att binda in Ca2+. Då Ca2+ är bundet kan proteinet binda och aktivera ytterligare protein med olika enskilda funktioner. CaM byter med hög hastighet till en mer öppen konformation då Ca2+ binder. Lite vetskap finns kring hur konformationsändringarna mellan apo-form och Ca2+-bunden form går till. En hypotes föreslår att protonering/deprotonering av en histidin-sidokedja kan vara en del av svaret och att CaMs dynamik därför bör vara beroende av pH. Detta undersöktes vidare i detta examensarbete. Metoder som användes för att genomföra projektet inkluderar proteinuttryck av isotopinmärkt CaM-TR2C E140Q, standardiserad proteinrening och proteinanpassad kärnmagnetisk resonans (NMR) spektroskopi. Resultaten föreslår att konformationsändringarna av CaM-TR2C E140Q troligen är pH-beroende och att histidin 107 (H107) kan ha en central roll vid dessa ändringar. Vid lägre pH föreslås att CaM-TR2C E140Q antar en mer öppen konformation med försvagade intramolekylära interaktioner och att tertiärstrukturen av CaM-TR2C E140Q kan ha blivit upplöst.

Place, publisher, year, edition, pages
2015. , 24 p.
Keyword [en]
Calmodulin, CaM-TR2C E140Q, protein dynamics, nuclear magnetic resonance, R1ρ
National Category
Structural Biology Biochemistry and Molecular Biology Physical Chemistry
URN: urn:nbn:se:liu:diva-121782ISRN: LITH-IFM-G-EX--15/3053—SEOAI: diva2:859050
Subject / course
Chemical Biology
Available from: 2015-10-13 Created: 2015-10-05 Last updated: 2015-10-13Bibliographically approved

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