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The development of new radical cross-linkers for structural characterization of proteins
Karpíšek, Michael ; Kukačka, Zdeněk (advisor) ; Chmelík, Josef (referee)
Proteins are important biomolecules because they carry out many essential functions. Since the structure of these biomolecules is usually closely linked to their function, there are numerous techniques to determine their three-dimensional structure. Exploiting the advantages of mass spectrometry, chemical cross-linking coupled to mass spectrometry is one of the methods that is used for structural characterization of studied molecule. Currently there is no reagent that targets and links all of the aromatic proteinogenic residues found in the sequence of proteins. In this work, we verified the reactivity of newly developed cross-linker towards aromatic residues and sulfhydryl group of cystein. This new reagent is based on the so-called Togni reagents that serve as trifluoralkylation agents. First, we monitored the impact of several different conditions on the composition of the reaction products using apomyoglobin as a model protein and electrosprey ionization as the method of choice. Subsequently we employed bottom up approach to find out which residues were modified. For this purpose we chose apomyoglobin and two other proteins that contain cysteine in its reduced form - RhoA and HSC70. Based on obtained results, we could confirm the ability of the new cross-linker to modify both aromatic residues...
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The development of new isotope-coded cross-linkers for label free quantification of proteins
Procházková, Valérie ; Kukačka, Zdeněk (advisor) ; Vaňková, Pavla (referee)
Elucidating the structure of proteins in living organisms is an important step in describing their role. One method of structural biology is chemical cross-linking in combination with mass spectrometry, which is a commonly used tool for characterisation of the tertiary structure of proteins or protein-protein interactions. This method is based on the reaction of a cross-linking agent consisting of two reactive groups linked by an arm of a defined length to form a covalent bond. The main aim of the project was to verify whether chemical cross-linking using istopically labeled cross-linking agents can be used for quantification of two different structural states. The reagents used in this work were DSPU and an isotopically labeled form of DSPUx. Both the DSPU and DSPUx reagents contain a labile urea molecule in their structure, which is cleaved into characteristic fragments during collision-induced dissociation, allowing the identification of cross-linked peptides. Using top-down and bottom-up approaches, it was found on selected proteins (insulin, human carbonic anhydrase, and bovine serum albumin) that DSPU and DSPUx reagents interact with selected peptides and proteins and are suitable for quantification of structural changes. Subsequently, structural differences in the presence (holoform) and...
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The development of new tyrosin binding cross-linkers for structural characterization of proteins
Karpíšek, Michael ; Kukačka, Zdeněk (advisor) ; Talacko, Pavel (referee)
Proteins are cornerstones of all living organisms. A lot of energy is invested in studying structures of proteins, because their function is determined by their structure. One of the techniques used to access the structure of proteins is chemical cross-linking in combination with mass spectrometry. In spite of their number, most of the cross-linkers bind few aminoacids such as lysine, cysteine or glutamic and aspartic acid. In our work we tried to develop tyrosin-binding cross-linkers. Using top down and bottom up approaches we studied the influence of N-hydroxysuccinimide esters and imidazole on the reactivity of the cross-linker in different pH on model proteins. According to the acquired data there is a difference in overal reactivity and specifity between the used cross-linkers. The cross-linkers containing imidazole modified tyrosine more although the difference was small and binding of tyrosine was not selective. [IN CZECH]
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