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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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Preparation of the transcription factor FOXK1 DNA binding domain
Procházková, Valérie ; Novák, Petr (advisor) ; Košek, Dalibor (referee)
Transcription factors are proteins that regulate gene expression in different cell types. They play an important role in many cellular processes including regulation of cell cycle and cell differentiation. They possess DNA binding domains to recognize and bind specific DNA sequences. One type of DNA binding domain is the forkhead domain, which contains a region of 100-110 amino acid residues. This sequence is referred to DBD FOX and its spatial arrangement resembles a "winged helix". Proteins of the FOX family interact with double- stranded DNA via the α-helix H3, which represents highly conserved region within the proteins of this family. Other regions of the DBD further contribute in DNA binding, but as not significantly conserved, and their different properties are responsible for variable affinities of individual FOX proteins against binding motifs. Differences in three-dimensional structure may also alter biological functions of FOX proteins in the organism. FOX proteins are divided into 19 subfamilies, including the FOXK subfamily, consisting of two members, FOXK1 and FOXK2. FOXK proteins regulate aerobic glycolysis, cell proliferation and carcinogenesis. Their increased expression has been reported in cancer cells of skeletal tissue, stomach, colon, breast, lung, ovary, etc. However, the...
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