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1

Protein folding vs. COVID-19 and the Mediterranean diet

Roterman Irena, Konieczny Leszek

Bio-Algorithms and Med-Systems

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2020

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Vol. 16, no. 2

art. no. 20200029

EN

The experience of the ongoing pandemic gives rise to a variety of questions, touching - among others - upon its biological aspects. Among the most often raised issues is why the situation has deteriorated to such a degree in the Mediterranean basin and the American eastern seaboard. This work identifies possible links between the protein folding process and the aforementioned epidemic. Given the circumstances, it should be regarded as a popular science article.

2

The variability of protein structure with respect to the hydrophobic core

Banach M., Wiśniowski Z., Kalinowska B., Konieczny L., Roterman I.

Bio-Algorithms and Med-Systems

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2017

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Vol. 13, no. 2

63--67

EN

The application of the fuzzy oil drop model to the analysis of protein structure is shown using two proteins. The selection of these two examples is due to their opposite character. Two proteins were selected representing very high order and very high disorder with respect to the organized uni-central hydrophobic core in proteins (one centrally localized concentration of high hydrophobicity). These two cases are to show examples of the large spectrum of variability of local organization of the hydrophobic core in proteins. The importance of the observation presented in this paper is significant with respect to large sets of proteins discussed in separate publications.

3

Dissimilar sequence: similar structure of proteins

Banach M., Konieczny L., Roterman I.

Bio-Algorithms and Med-Systems

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2016

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Vol. 12, no. 3

117--121

EN

Sequence-to-structure relation is one of the major objects of the analysis of protein folding problem. The pair of two small proteins (domains) of similar structure (β-hairpin/α-helix/β-hairpin) generated by the chains of similar length (about 60 amino acids) with very low sequence similarity (15%) is the object of the comparable analysis of 3D structure. The criterion for similarity estimation is the status of polypeptide chain with respect to the hydrophobic core structure. The fuzzy oil drop model is applied to reveal the differentiated status of fragments of the well-defined secondary structure. This analysis allows the interpretation of the structure in other than the geometric form as it is made based on secondary structure classification. The two compared highly similar proteins appear to be different with respect to the hydrophobic core structure.

4

Hydrophobic core structure of macromomycin – the apoprotein of the antitumor antibiotic auromomycin – fuzzy oil drop model applied

Roterman-Konieczna I., Banach M., Konieczny L.

Bio-Algorithms and Med-Systems

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2015

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Vol. 11, no. 3

177--181

EN

The fuzzy oil drop model was applied to analyze the structure of macromomycin, the apoprotein of the antitumor antibiotic auromomycin, revealing the differentiation of β-structural fragments present in β-sandwich. The seven-stranded antiparallel β-barrel and two antiparallel β-sheet ribbons represent the highly ordered geometry of the structure. However, participation in hydrophobic core formation appears different. The structure of the complete domain represents the status of the irregular hydrophobic core; however, some β-structural fragments appear to represent the hydrophobicity density distribution accordant with the idealized distribution of hydrophobicity as expected using the fuzzy oil drop model. Four β-structural fragments generating one common layer appear to be unstable in respect to the general structure of the hydrophobic core. This area is expected to be more flexible than other parts of the molecule. The protein binds the ligand – chromophore, two 2-methyl-2,4-pentanediol – in a well- defined cleft. The presence of this cleft makes the general structure of the hydrophobic core irregular (as it may be interpreted using the fuzzy oil drop model). Two short loops generated by two SS bonds fit very well to the general distribution of hydrophobicity density as expected for the model. No information about the potential amyloidogenic character of this protein is given in the literature; however, the specificity of the hydrophobicity distribution profile is found to be highly similar to the one observed in transthyretin (Banach M, Konieczny L, Roterman I. The fuzzy oil drop model, based on hydrophobicity density distribution, generalizes the influence of water environment on protein structure and function. J Theor Biol 2014;359:6–17), suggesting a possible tendency to turn to the amyloid form. A detailed analysis of macromomycin will be given, and a comparable analysis with other proteins of β-sandwich or β-barrel will be presented.

5

Application of divergence entropy to characterize the structure of lipid-binding proteins

Rosicka R., Banach M., Roterman-Konieczna I.

Bio-Algorithms and Med-Systems

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2015

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Vol. 11, no. 3

171--176

EN

The lipid-binding protein present in the human brain is the object of this analysis. The expression of these proteins is especially important for nervous cell differentiation and their migration in the process of the development of the brain. The “fuzzy oil drop” model applied to the analysis of these proteins may suggest the mechanism of complex generation. It is shown that this type of complex may appear spontaneously in water environment. The presence of ligand does not imply any form of adaptation of the polypeptide chain to the ligand molecule. It can be speculated that ligand binding is of a static character without the necessity for mutual structural fitting. The structures of polypeptide in the apo- and complexed forms do not differ in respect to hydrophobic core formation. Such an interpretation is different than that observed in other ligand-binding proteins where the binding cavity needs to be specially fitted to the specific ligand. It can also be concluded that the lipid-binding process is of low specificity in this case.

6

Protein intrachain contact prediction with most interacting residues (MIR)

Acuña R., Lacroix Z., Papandreou N., Chomilier J.

Bio-Algorithms and Med-Systems

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2014

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Vol. 10, no. 4

227--242

EN

The transition state ensemble during the folding process of globular proteins occurs when a sufficient number of intrachain contacts are formed, mainly, but not exclusively, due to hydrophobic interactions. These contacts are related to the folding nucleus, and they contribute to the stability of the native structure, although they may disappear after the energetic barrier of transition states has been passed. A number of structure and sequence analyses, as well as protein engineering studies, have shown that the signature of the folding nucleus is surprisingly present in the native three-dimensional structure, in the form of closed loops, and also in the early folding events. These findings support the idea that the residues of the folding nucleus become buried in the very first folding events, therefore helping the formation of closed loops that act as anchor structures, speed up the process, and overcome the Levinthal paradox. We present here a review of an algorithm intended to simulate in a discrete space the early steps of the folding process. It is based on a Monte Carlo simulation where perturbations, or moves, are randomly applied to residues within a sequence. In contrast with many technically similar approaches, this model does not intend to fold the protein but to calculate the number of non-covalent neighbors of each residue, during the early steps of the folding process. Amino acids along the sequence are categorized as most interacting residues (MIRs) or least interacting residues. The MIR method can be applied under a variety of circumstances. In the cases tested thus far, MIR has successfully identified the exact residue whose mutation causes a switch in conformation. This follows with the idea that MIR identifies residues that are important in the folding process. Most MIR positions correspond to hydrophobic residues; correspondingly, MIRs have zero or very low accessible surface area. Alongside the review of the MIR method, we present a new postprocessing method called smoothed MIR (SMIR), which refines the original MIR method by exploiting the knowledge of residue hydrophobicity. We review known results and present new ones, focusing on the ability of MIR to predict structural changes, secondary structure, and the improved precision with the SMIR method.

7

Scenariusze użycia systemu MAS4PSi w diagnostyce medycznej

Górczyńska-Kosiorz S., Małysiak-Mrozek B., Mrozek D.

Studia Informatica

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2013

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Vol. 34, nr 2A

337--352

PL

System MAS4PSi (Multi Agent System For Protein Similarity searching) pozwala na szybkie, skalowalne i niezawodne poszukiwanie podobieństwa strukturalnego białek. Poszukiwanie podobieństwa strukturalnego białek jest kluczowe w prowadzeniu badań nad różnymi procesami biologicznymi i innymi obszarami, które mają swoją podstawę w tych procesach biologicznych. Celem niniejszego artykułu jest przybliżenie i określenie możliwych scenariuszy wykorzystania zbudowanego systemu MAS4PSi w powszechnie rozumianej diagnostyce medycznej zarówno na etapie opracowywania eksperymentów pomocnych we wprowadzeniu nowych badań, jak i na etapie typowo diagnostycznym.

EN

MAS4PSi (Multi-Agent System For Protein Similarity searching) is a system that allows fast, scalable and reliable protein structure similarity searching. Protein structure similarity searching is crucial in conducting research on a variety of biological processes, and other areas that have their basis in these biological processes. The purpose of this article is to define and present possible scenarios of using the MAS4PSi system in a broadly understood medical diagnostics, both in the design of experiments supporting new research, as well as the typical diagnostic stage.

8

The identification and the elimination of clashes in the structure of an early-stage intermediate in the protein folding process

Baster Z.

Bio-Algorithms and Med-Systems

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2013

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Vol. 9, no. 4

199--207

EN

The model (under consideration) to simulate the protein folding process assumes two steps: early stage (ES) and late stage (LS). The first is assumed to define the preliminary structure, which when applied to an optimization procedure, may produce the proper structure of the protein. However, the ES model produces the structures with clashes. This work demonstrates the possible solution to remove clashes before proceeding to the LS. Additionally, the presented solution describes mathematically the precession phenomenon, which might be useful in other fields of studies aside from protein folding such as medical imaging, quantum physics, and astronomy.

9

Efektywna reprezentacja molekularnych struktur białkowych stosowana w procesie ich porównania

Małysiak-Mrozek B., Mrozek D., Kołkowski Ł.

Studia Informatica

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2012

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Vol. 33, nr 2A

507-524

PL

Porównanie molekularnych struktur białkowych często jest ważnym procesem towarzyszącym poszukiwaniu podobieństwa strukturalnego białek, identyfikacji ich funkcji, a także badaniu ewolucji organizmów żywych. Efektywna reprezentacja struktur białkowych jest niezwykle istotna dla powodzenia procesu porównania oraz szybkości jego prowadzenia. W niniejszym artykule przedstawiono rozważania na temat wyboru cech reprezentatywnych opisujących struktury białkowe w procesie ich porównywania. Zaprezentowano również badania dotyczące porównania struktur białkowych za pomocą macierzy odległości międzyrezydualnych, transformowanych następnie do macierzy odcieni szarości i opisanych przez współczynnik jakości obrazu Q dla szybszego porównania i wyszukiwania w bazie danych.

EN

Comparison of protein, molecular structures is often an essential component process of protein structure similarity searching, identification of protein functions, and investigation of the evolution of living organisms. Effective representation of protein structures in the comparison process is then very important for its successfulness and swiftness. In the paper, we present considerations on using various, representative features describing protein structures in their comparison. We also show our research on protein structure comparison with the use of intra-residual distance matrices, which are transformed to the grayscale images and described by means of the Universal Image Quality Index for faster comparison and database retrieval.

10

Dwufazowy algorytm dopasowania w poszukiwaniu podobieństwa struktur białkowych

Krygowski A., Małysiak-Mrozek B., Mrozek D.

Studia Informatica

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2012

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Vol. 33, nr 2A

525-541

PL

Poszukiwanie podobieństwa strukturalnego białek jest jednym z kluczowych, a zarazem trudnych zadań współczesnej bioinformatyki strukturalnej. Bogata przestrzeń poszukiwań oraz różnorodność cech strukturalnych i funkcjonalnych białek sprawiają, że powstaje wiele algorytmów poszukiwania podobieństwa białek, których działanie opiera się na różnych cechach reprezentatywnych. W niniejszym artykule przedstawiono nowy, dwufazowy algorytm dopasowania struktur białkowych, wykorzystywany w poszukiwaniu podobieństwa białek.

EN

Protein structure similarity searching is one of the key, and yet difficult tasks of modern structural bioinformatics. A reach exploration space and a wide variety of structural and functional features of proteins caused the development of many algorithms of protein similarity searching, whose activity is based on various representative characteristics. In this paper, we present a new, two-phase algorithm for matching protein structures used in the protein similarity searching.

11

Architektura hierarchicznego systemu wieloagentowego dla procesu poszukiwania podobieństwa białek

Małysiak-Mrozek B., Momot A., Mrozek D., Momot M.

Studia Informatica

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2012

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Vol. 33, nr 2A

83-97

PL

Poszukiwanie podobieństwa strukturalnego białek jest procesem niezwykle złożonym obliczeniowo i czasochłonnym, a jednocześnie istotnym z punktu widzenia zrozumienia działania i funkcji cząstek białkowych. Jednym ze sposobów przyspieszenia tego procesu jest jego zrównoleglenie przez rozproszenie obliczeń na wielu komputerach. W niniejszym artykule przedstawiono zaprojektowaną przez autorów architekturę hierarchicznego systemu wieloagentowego wykorzystywanego w poszukiwaniu podobieństwa białek. Zaprezentowano również różne scenariusze użycia i implementacji tej architektury w poszukiwaniu podobieństwa molekuł biologicznych. Dodatkowo przedstawiono wyniki eksperymentów numerycznych potwierdzających przydatność zaprojektowanej architektury w procesie eksploracji struktur białkowych.

EN

Protein structure similarity searching is a very complex and time-consuming process. One of the possibilities how we can accelerate the process is parallelization by distributing the computational procedure on multiple computers. In the paper, we present the architecture of the hierarchical multi-agent system dedicated to protein structure similarity searching. We also demonstrate different scenarios how this architecture can be used and modified in similarity searching of biological molecules. Additionally, we show results of several numerical experiments confirming a suitability of the presented architecture in the exploration of protein structures.

12

Stability of two natural homologous proteins with different folds

Konieczny L., Banach M., Roterman I.

Bio-Algorithms and Med-Systems

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2012

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Vol. 8, no. 2

185--193

EN

The applicability of the model for protein folding process simulation is presented using as the test two homologous proteins of different fold: helical in 3BD1 and β-structural form in 2PIJ [L. van Dorn, T. Newlove, S. Chang, W. Ingram, M. Cordes. Biochemistry 45, 10542 (2006)]. The folding process is assumed to be directed by hydrophobic core directing the hydrophobic residues toward the center of the molecule and exposing the hydrophilic residues on the surface. The “fuzzy oil drop” model is expressed by the 3-dimensional Gauss function which mimics the external force field. The value of Gauss function is interpreted as the hydrophobicity density calculated in any point of the space of the protein body. The accordance of idealized and observed hydrophobicity distributions (calculated according to Levitt function) measured using the Kullback-Leibler divergence entropy reveals good accordance in two homological proteins of different folds. The structural differences appeared to be easily explainable on the basis of “fuzzy oil drop” model.

13

Measurement of hydrophobicity distribution in proteins – complete redundant Protein Data Bank

Sałapa K, Kalinowska B., Jadczyk T., Roterman I.

Bio-Algorithms and Med-Systems

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2012

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Vol. 8, no. 2

195--206

EN

The divergence entropy: O/T and O/R measuring the distance between observed/theoretical and observed/random distributions was applied to identify the category of protein structures in respect to the hydrophobic core in protein molecules. The naive interpretation was applied treating the proteins of O/T < O/R as the molecules of hydrophobic core accordant with the theoretically assumed. The proteins of O/T > O/R are treated as representing the hydrophobic core not accordant with the assumed one. The large scale computing was performed (PDB data set) to reveal whether other than simple inequality relation should be used for this identification. The cluster analysis was applied to identify the relation O/T versus O/R as the discrimination factor to classify the category of proteins in respect to their structural form of hydrophobic core.

14

Using machine learning approach for protein fold recognition

Stąpor K.

Studia Informatica

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2011

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Vol. 32, nr 4A

27-41

EN

Protein fold recognition using machine learning-based methods is crucial in the protein structure discovery, especially when the traditional sequence comparison methods fail because the structurally-similar proteins share little in the way of seąuence homology. Based on the selected machine learning classification methods, we explain the methodology for building classifiers which can be used in the protein fold recognition problem.

PL

Rozpoznawanie typu ufałdowania białka z wykorzystaniem metod uczenia maszynowego ma kluczowe znaczenie w przewidywaniu struktury białka, szczególnie w przypadkach kiedy tradycyjne podejście oparte na podobieństwie łańcuchów nie znajduje zastosowania ze względu na jego znikomą wartość. Na podstawie wybranych algorytmów uczenia maszynowego klasyfikacji w artykule przedstawiono metodykę automatycznego rozpoznawania typu ufałdowania białka.

15

Ab initio protein structure prediction – the hydrophobicity distribution analysis

Evangelista G., Minervini G., Polticelli F, Malawski M., Szepieniec T., Flis Ł., Prymula K., Kochańczyk M., Matczyńska E., Wiśniowski Z., Salapa K., Banach M., Roterman I.

Bio-Algorithms and Med-Systems

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2011

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Vol. 7, no. 2

5--12

EN

The three-dimensional structures generated for 20 “never born proteins” (NBP – random amino acid sequence with no significant homology to existing proteins) using two different techniques: ROSETTA (called R in the paper) and “fuzzy oil drop” model (called S in the paper) were compared to estimate the accordance with the assumed model estimating the influence of an external force field on the final structure of the protein. Selected structures are those corresponding to the highest (10 proteins) and lowest (10 proteins) RMS-D values obtained measuring the similarity between the R and S structures. The R structures generated according to an internal force field (the individual inter-molecular interaction) including solvation effects were analyzed using the “fuzzy oil drop” model as target model. The second applied model “fuzzy oil drop” generated structures characterized by an ordered hydrophobic core structure. 13 of the 20 selected S structures appeared to be accordant with the “fuzzy oil drop” model while 6 out of the 20 structures appeared to be accordant with external force field for R structures which suggests a general interpretation of the influence of an external force field on the folding simulation.

16

EDB – baza danych rozkładów energii potencjalnej białek

Mrozek D., Małysiak-Mrozek B., Kozielski S., Kral K., Moczała M., Oleś Ł., Suwała T., Szecówka A.

Studia Informatica

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2009

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Vol. 30, nr 2B

163-178

PL

Analiza cech strukturalnych i energetycznych białek może być kluczem do zrozumienia, w jaki sposób białka oddziaływają ze sobą w reakcjach komórkowych. Podczas badania złożonych procesów, w których uczestniczą białka, niezwykle pomocne mogą być rozkłady energii potencjalnej na poszczególnych atomach struktury. Baza Energy Distribution Data Bank (EDB, http://edb.aei.polsl.pl) przechowuje rozkłady energii różnych typów dla struktur białkowych pobranych ze znanej amerykańskiej bazy Protein Data Bank. W niniejszym artykule opisujemy cel zbudowanej przez nas bazy EDB, możliwe sposoby jej wykorzystania w badaniach naukowych, możliwości wyszukiwania właściwej informacji i plany dalszego rozwoju.

EN

The analysis of structural and energy features of proteins can be a key to understand how proteins work and interact to each other in cellular reŹactions. The distributions of energy over each atom in protein structures can be very supportive for the studies of the complex processes proteins are involved in. The Energy Distribution Data Bank (EDB, http://edb.aei.polsl.pl) stores a variety of energy distributions for protein molecular structures retrieved from the well-known Protein Data Bank. In the paper, we describe the purpose of the EDB, a possible use of the information stored in it, query possibilities, and plans for future development.

17

Kompleksy białek i układów ciekłokrystalicznych. Możliwość zastosowań praktycznych

Drozd A., Konieczny L., Rybarska J., Stopa B., Piekarska B., Roterman I., Król M., Spólnik P., Zemanek G.

Bio-Algorithms and Med-Systems

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2005

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Vol. 1, no. 1/2

113--116

PL

Wg powszechnie przyjętego mechanizmu tworzenia się specyficznych kompleksów z białkami, miejscem wiązania ligandów, w tym również pochodzenia niebiologicznego (a więc np. leków) jest grupa czynna białka. To miejsce w białku umożliwia wiązanie liganda przy ograniczonym dostępie wody, która skutecznie zapobiega asocjacjom powierzchniowym. W związku z dynamicznym charakterem struktury białka istnieje jednak możliwość penetracji ligandów do obszarów głębszych poza grupą czynną. Kompleksowanie napotyka jednak tutaj na konkurencję łańcucha polipeptydowego, który jedynie w wyniku fluktuacji przejściowo umożliwił penetrację liganda. Konkurencji nie wytrzymują z reguły związki drobnocząsteczkowe. Jednak może jej sprostać zespołowa interakcja, jaką reprezentują zasocjowane cząsteczki liganda supramole- kularnego pod warunkiem, że wzajemnie oddziaływujące cząsteczki liganda - nadające mu spójność - są odpowiednio duże. Ligandy supramolekularne, które tworzą micele taśmowe, korespondują strukturalnie z łańcuchem peptydowym o konformacji Beta. Te szczególne rodzaje struktur ciekłokrystalicznych nadają się do tworzenia kompleksów poza grupą czynną białek. Plastyczność tych ligandów wybitnie ułatwia kompleksowanie. Ponieważ dynamika natywnego białka ujawnia się głównie w wyniku ruchów związanych z funkcją, utworzone kompleksy zamrażające przejściowy stan dynamiczny mają istotny wpływ na biologiczną aktywność białka. Kompleksowanie ligandów supramolekularnych o własnościach ciekłokrystalicznych jest problemem nowym. Zjawisko otwiera duże możliwości zastosowań praktycznych.

EN

The protein binding site is (according to commonly accepted mechanism) the only locus responsible for the specific ligation of compounds of non-biological origin, including drugs. The binding cleft favors association decreasing the access of water which prevents efficiently the non-covalent binding at the protein surface. Nevertheless, the dynamic character of protein structure may allow penetration of small compounds to the periphery or the interior of the molecule, outside the binding site. However, the complexation meets here the strong competition of polypeptide chains making the non-specific interaction of small molecules unsufficient to ensure the binding. This competition may be faced after all by collective interaction of self-assembled molecules if the local or global instability of protein structure allows penetration of a large unit of su- pramolecular ligand and self-assembling is strong enough to replace the polypeptide chain from its packing locus. The supramolecular ligands of Congo red family which form ribbon- shaped micellar entities and correspond in some way to polypeptide chains of Beta-conformation offer the largest interaction contact. Supramolecular structures of this kind appear capable of sustaining the competition of polypeptide chains and form stable complexes. The strong complexation depends particularly on plasticity of dye ligand improving the fitting to receptor sites in protein. Since the increased structural dynamics of native protein, allowing the penetration of dye is commonly associated with function-derived movements, the complexation may affect biological activity. The recently discovered complexation of supramolecular structures with proteins seems to be a promising phenomenon for pharmacology and medicine.

18

Non-classic constraints in protein structure determination

Ejchart A.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 1

1-11

EN

Recently, three new types of structural constraints have been introduced into the procedures of protein structure determination. Application of residual dipolar cou-plings, interference effects, and dependence of heteronuclear relaxation times on rotational diffusion anisotropy opens new perspectives for the functional and structural NMR studies of proteins.

19

Scalar couplings in structure determination of proteins

Ejchart A.

Bulletin of the Polish Academy of Sciences. Chemistry

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1999

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Vol. 47, No. 1

1-19

EN

Derivation of scalar couplings and their applications as structural constraints used in the determination of high resolution protein structures from nuclear magnetic resonance data is discussed.

20

Struktura, dynamika i termodynamika białek globularnych: siatkowe modele Monte Carlo

Koliński A.

Polimery

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1998

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T. 43, nr 6

341-351

PL

Scharakteryzowano własny, opisany już w literaturze symulacyjny model białka, oparty na dyskretyzacji siatkowej i metodzie Monte Carlo. Oddziaływania pomiędzy tzw. atomami połączonymi wyprowadzono w nim w postaci potencjałów statystycznych wynikających z analizy regularności strukturalnych obserwowanych w znanych strukturach jednodomenowych białek globularnych. Przedstawiono kilka przykładowych zastosowań i przedyskutowano zakres stosowalności modelu oraz kierunki jego dalszego rozwoju. Bardziej szczegółowo opisano wyniki symulacji procesu asocjacji podwójnej helisy fragmentu białka transkrypcyjnego GCN4

EN

A Monte Carlo high-resolution lattice model of protein structure and dynamics is described. Interactions between combined atoms are described in terms of statistical potentials derived from the analysis of the structural regularities occurring in the known structures of single-domain globular proteins. Illustrative applications, applicability range, and possible further development of the model are given. Results of the simulations of the coil assembly of the leucine zipper fragment of transcriptional activator GCN4 are discussed in more detail.