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1
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Crystallization and preliminary crystallographic studies of a new crystal form of papain from Cariea papaya

100%
Kozak M., Kozian E., Grzonka Z., Jaskólski M.
Acta Biochimica Polonica
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1997
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vol. 44
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issue 3
601-605
2
Content available remote

Circular dichroism and aggregation studies of amyloid β (11-8) fragment and its variants.

100%
Juszczyk P., Kołodziejczyk A. S., Grzonka Z.
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2005
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vol. 52
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issue 2
425-431
EN
Aggregation of Aβ peptides is a seminal event in Alzheimer's disease. Detailed understanding of Aβ assembly would facilitate the targeting and design of fibrillogenesis inhibitors. Here comparative conformational and aggregation studies using CD spectroscopy and thioflavine T fluorescence assay are presented. As a model peptide, the 11-28 fragment of Aβ was used. This model peptide is known to contain the core region responsible for Aβ aggregation. The structural and aggregational behaviour of the peptide was compared with the properties of its variants corresponding to natural, clinically relevant mutants at positions 21-23 (A21G, E22K, E22G, E22Q and D23N). In HFIP (hexafluoro-2-propanol), a strong α-helix inducer, the CD spectra revealed an unexpectedly high amount of β-sheet conformation. The aggregation process of Aβ(11-28) variants provoked by water addition to HFIP was found to be consistent with a model of an α-helix-containing intermediate. The aggregation propensity of all Aβ(11-28) variants was also compared and discussed.
3
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Oxytocin analogues with amide groups substituted by tetrazole groups in position 4, 5 or 9

100%
Manturewicz M., Grzonka Z., Borovičková L., Slaninová J.
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2007
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vol. 54
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issue 4
805-811
EN
Eleven oxytocin analogues substituted in position 4, 5 or 9 by tetrazole analogues of amino acids were prepared using solid-phase peptide synthesis method and tested for rat uterotonic in vitro and pressor activities, as well as for their affinity to human oxytocin receptor. The tetrazolic group has been used as a bioisosteric substitution of carboxylic, ester or amide groups in structure-activity relationship studies of biologically active compounds. Replacement of the amide groups of Gln4 and Asn5 in oxytocin by tetrazole analogues of aspartic, glutamic and α-aminoadipic acids containing the tetrazole moiety in the side chains leads to analogues with decreased biological activities. Oxytocin analogues in which the glycine amide residue in position 9 was substituted by tetrazole analogues of glycine had diminished activities as well. The analysis of differences in rat uterotonic activity and in the affinity to human oxytocin receptors of analogues containing either an acidic 5-substituted tetrazolic group or a neutral 1,5- or 2,5-tetrazole nucleus makes it possible to draw some new conclusions concerning the role of the amide group of amino acids in positions 4, 5 and 9 of oxytocin for its activity. The data suggest that the interaction of the side chain of Gln4 with the oxytocin receptor is influenced mainly by electronic effects and the hydrogen bonding capacity of the amide group. Steric effects of the side chain are minor. Substitution of Asn5 by its tetrazole derivative gave an analogue of very low activity. The result suggests that in the interaction between the amide group of Asn5 and the binding sites of oxytocic receptor hydrogen bonds are of less importance than the spatial requirements for this group.
4
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Effect of antisense peptide binding on the dimerization of human cystatin C - gel electrophoresis and molecular modeling studies.

76%
Stachowiak K., Rodziewicz-Motowidło S., Sosnowska R., Kasprzykowski F., Łankiewicz L., Grubb A., Grzonka Z.
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vol. 51
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issue 1
153-160
EN
Human cystatin C (HCC) shows a tendency to dimerize. This process is particularly easy in the case of the L68Q HCC mutant and might lead to formation of amyloid deposits in brain arteries of young adults. Our purpose was to find ligands of monomeric HCC that can prevent its dimerization. Eleven antisense peptide ligands of monomeric HCC were designed and synthesized. The influence of these ligands on HCC dimerization was studied using gel electrophoresis and molecular modeling methods. The results suggest that all the designed peptides interact with monomeric HCC facilitating its dimerization rather than preventing it.
5
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Governing the monomer-dimer ratio of human cystatin c by single amino acid substitution in the hinge region

76%
Szymańska A., Radulska A., Czaplewska P., Grubb A., Grzonka Z., Rodziewicz-Motowidło S.
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issue 3
455-463
EN
Three dimensional domain swapping is one of the mechanisms involved in formation of insoluble aggregates of some amyloidogenic proteins. It has been proposed that proteins able to swap domains may share some common structural elements like conformationally constrained flexible turns/loops. We studied the role of loop L1 in the dimerization of human cystatin C using mutational analysis. Introduction of turn-favoring residues such as Asp or Asn into the loop sequence (in position 57) leads to a significant reduction of the dimer fraction in comparison with the wild type protein. On the other hand, introduction of a proline residue in position 57 leads to efficient dimer formation. Our results confirm the important role of the loop L1 in the dimerization process of human cystatin C and show that this process can be to some extent governed by single amino acid substitution.
6
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Structural studies of cysteine proteases and their inhibitors.

52%
Grzonka Z., Jankowska E., Kasprzykowski F., Kasprzykowska R., Łankiewicz L., Wiczk W., Wieczerzak E., Ciarkowski J., Drabik P., Janowski R., Kozak M., Jaskólski M., Grubb A.
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2001
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vol. 48
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issue 1
1-20
EN
Cysteine proteases (CPs) are responsible for many biochemical processes occurring in living organisms and they have been implicated in the development and progression of several diseases that involve abnormal protein turnover. The activity of CPs is regulated among others by their specific inhibitors: cystatins. The main aim of this review is to discuss the structure-activity relationships of cysteine proteases and cystatins, as well as of some synthetic inhibitors of cysteine proteases structurally based on the binding fragments of cystatins.
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