Dwie twarze struktury przestrzennej białek – zastosowanie wiedzy o białkach samoistnie nieuporządkowanych w racjonalnym projektowaniu leków

Proteins are an essential component of living cells. Proper understanding of the properties of their structure is crucial to understanding their function in nature. The proteins and their fragments may exist in four states of structure organization: ordered, molten globule, pre molten globule and random coil. The particular function of proteins depend on any one of these states or a transition betweenthem. A significant proportion of proteins in nature is composed of a mixture of ordered and intrinsically disordered regions, that fulfil important roles in the processes like signal transduction, cell cycle regulation and many others. The standard approach for rational drugdesign does not work for intrinsically disordered proteins (IDPs) and requires modified strategies. Furthermore, the majority of proteins with long intrinsically disordered regions (IDRs) use short molecular recognition elements (MoRFs), which undergo transition from disorder toorder state and adopt various structures in numerous protein protein interactions. These interactions are an attractive therapeutic target for the pharmaceutical industry in the process of rational drug design.Białka są podstawowymi składnikami żywych komórek. Prawidłowe rozumienie cech ich struktury przestrzennej jest kluczowe dla zrozumienia ich funkcjonowania w organizmach żywych. Białka mogą przebywać w czterech wyróżnionych stanach organizacji struktury przestrzennej: uporządkowanym, stopionej globuli, pre-stopionej globuli i kłębka statystycznego. Funkcje białek mogą być związane z każdym tych stanów, a co ważniejsze, z przejściami pomiędzy tymi stanami. Znacząca liczba białek w przyrodzie zbudowana jest z mieszaniny rejonów uporządkowanych oraz samoistnie nieuporządkowanych, które pełnią ważne role w procesach przekazu sygnału, regulacji cyklu komórkowego i wielu innych. Standardowe podejście do racjonalnego projektowania leków nie sprawdza się w przypadku białek samoistnie nieuporządkowanych (IDPs) i wymaga zmodyfikowanej strategii postępowania. Jednym z atrakcyjnych celów terapeutycznych dla przemysłu farmaceutycznego są krótkie fragmenty łańcucha aminokwasowego pełniące funkcje elementów rozpoznawania molekularnego (MoRFs), które porządkują swoją strukturę w różnorodnych i licznych oddziaływaniach z innymi białkami. Charakterystyczną cechą MoRFs-ów jest ich częste występowanie w rejonach samoistnie nieuporządkowanych łańcucha polipeptydowego

Quantitative analysis of the ternary complex of RNA polymerase, cyclic AMP receptor protein and DNA by fluorescence anisotropy measurements

The in vitro formation of transcription complexes with Escherichia coli RNA polymerase was monitored using fluorescence anisotropy measurements of labeled fragments of DNA. The multicomponent system consisted of holo or core RNA polymerase (RNAP) and lac or gal promoter fragments of DNA (in different configurations), in the presence or absence of CRP activator protein (wt or mutants) with its ligand, cAMP. Values of the apparent binding constants characterizing the system were obtained, as a result of all processes taking place in the system. The interaction of the promoters with core RNAP in the absence of CRP protein was characterized by apparent binding constants of 0.67 and 1.9 × 106 M-1 for lac166 and gal178, respectively, and could be regarded as nonspecific. The presence of wt CRP enhanced the strength of the interaction of core RNAP with the promoter, and even in the case of gal promoter it made this interaction specific (apparent binding constant 2.93 × 107 M-1). Holo RNAP bound the promoters significantly more strongly than core RNAP did (apparent binding constants 1.46 and 40.14 × 106 M-1 for lac166 and gal178, respectively), and the presence of CRP also enhanced the strength of these interactions. The mutation in activator region 1 of CRP did not cause any significant disturbances in the holo RNAP-lac promoter interaction, but mutation in activator region 2 of the activator protein substantially weakened the RNAP-gal promoter interaction

The use of a barley-based well to define cationic betaglucan to study mammalian cell toxicity associated with interactions with biological structures

Among potential macromolecule-based pharmaceuticals, polycations seem particularly interesting due to their proven antimicrobial properties and use as vectors in gene therapy. This makes an understanding of the mechanisms of these molecules’ interaction with living structures important, so the goal of this paper was to propose and carry out experiments that will allow us to characterize these phenomena. Of particular importance is the question of toxicity of such structures to mammalian cells and, in the work presented here, two lines, normal fibroblasts 3T3-L1 and A549 lung cancer, were used to determine this. In this work, three well-defined cationic derivatives of barley-derived betaglucans obtained in a reaction with glycidyltrimethylammonium chloride (BBGGTMAC) with different degrees of cationization (50, 70, and 100% per one glucose unit) and electrostatic charge were studied. The studies address interactions of these polymers with proteins (bovine serum proteins and BSA), nucleic acids (DNA), glycosaminoglycans (heparin), and biological membranes. The results described in this study make it possible to indicate that toxicity is most strongly influenced by interactions with biological membranes and is closely related to the electrostatic charge of the macromolecule. The presentation of this observation was the goal of this publication. This paper also shows, using fluorescently labeled variants of polymers, the penetration and impact on cell structure (only for the polymer with the highest substitution binding to cell membranes is observed) by using confocal and SEM (for the polymer with the highest degree of substitution, and the appearance of additional structures on the surface of the cell membrane is observed). The labeled polymers are also tools used together with dynamic light scattering and calorimetric titration to study their interaction with other biopolymers. As for the interactions with biological membranes, lipid Langmuir monolayers as model membrane systems were used

Engineered β\beta-lactoglobulin produced in E-coli : purification, biophysical and structural characterisation

Functional recombinant bovine β-lactoglobulin has been produced by expression in E. coli using an engineered protein gene and purified to homogeneity by applying a new protocol. Mutations L1A/I2S introduced into the protein sequence greatly facilitate in vivo cleavage of the N-terminal methionine, allowing correctly folded and soluble protein suitable for biochemical, biophysical and structural studies to be obtained. The use of gel filtration on Sephadex G75 at the last purification step enables protein without endogenous ligand to be obtained. The physicochemical properties of recombinant β-lactoglobulin such as CD spectra, ligand binding (n, K(a), ΔH, TΔS, ΔG), chemical and thermal stability (ΔG(D), C(mid)) and crystal structure confirmed that the protein obtained is almost identical to the natural one. The substitutions of N-terminal residues did not influence the binding properties of the recombinant protein so that the lactoglobulin produced and purified according to our protocol is a good candidate for further engineering and potential use in pharmacology and medicine. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s12033-016-9960-z) contains supplementary material, which is available to authorized users