Olga Szczepankiewicz

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Calbindin D(28k) (calbindin) is a member of the calmodulin superfamily of Ca(2+)-binding proteins. An intracellular target of calbindin was discovered using bacteriophage display. Human recombinant calbindin was immobilized on magnetic beads and used in affinity purification of phage-displayed peptides from a random 12-mer peptide library. One sequence,(More)
A small number of proteins have the unusual property of tasting intensely sweet. Despite many studies aimed at identifying their sweet taste determinants, the molecular basis of protein sweetness is not fully understood. Recent mutational studies of monellin have implicated positively charged residues in sweetness. In the present work, the effect of overall(More)
Amyloid β-protein (Aβ) sequence length variants with varying aggregation propensity coexist in vivo, where coaggregation and cross-catalysis phenomena may affect the aggregation process. Until recently, naturally occurring amyloid β-protein (Aβ) variants were believed to begin at or after the canonical β-secretase cleavage site within the amyloid β-protein(More)
Nanoparticles interfere with protein amyloid formation. Catalysis of the process may occur due to increased local protein concentration and nucleation on the nanoparticle surface, whereas tight binding or a large particle/protein surface area may lead to inhibition of protein aggregation. Here we show a clear correlation between the intrinsic protein(More)
Protein stabilization was achieved through in vivo screening based on the thermodynamic linkage between protein folding and fragment complementation. The split GFP system was found suitable to derive protein variants with enhanced stability due to the correlation between effects of mutations on the stability of the intact chain and the effects of the same(More)
This study shows significant effects of protein surface charges on stability and these effects are not eliminated by salt screening. The stability for a variant of protein G B1 domain was studied in the pH-range of 1.5-11 at low, 0.15 M, and 2 M salt. The variant has three mutations, T2Q, N8D, and N37D, to guarantee an intact covalent chain at all pH(More)
The relative significance of weak non-covalent interactions in biological context has been much debated. Here, we have addressed the contribution of Coulombic interactions to protein stability and assembly experimentally. The sweet protein monellin, a non-covalently linked heterodimeric protein, was chosen for this study because of its ability to(More)
A series of recent studies have provided initial evidence about the role of specific intra-molecular interactions in maintaining proteins in their soluble state and in protecting them from aggregation. Here we show that the amino acid sequence of the protein monellin contains two aggregation-prone regions that are prevented from initiating aggregation by(More)
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