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1
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Influence of Me2SO and incubation time on papain activity studied using fluorogenic substrates.

100%
Szabelski M., Stachowiak K., Wiczk W.
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2001
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vol. 48
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issue 4
995-1002
EN
Papain activity in a buffer containing Me2SO was studied using fluorogenic substrates. It was found that the number of active sites of papain decreases with increasing Me2SO concentration whereas the incubation time, in a buffer containing 3% Me2SO does not affect the number of active sites. However, an increase of papain incubation time in the buffer with 3% Me2SO decreased the initial rate of hydrolysis of Z-Phe-Arg-Amc as well as Dabcyl-Lys-Phe-Gly-Gly-Ala-Ala-Edans. Moreover, an increase of Me2SO concentration in working buffer decreased the initial rate of papain-catalysed hydrolysis of both substrates. A rapid decrease of the initial rate (by up to 30%) was observed between 1 and 2% Me2SO. Application of the Michaelis-Menten equation revealed that at the higher Me2SO concentrations the apparent values of kcat/Km decreased as a result of Km increase and kcat decrease. However, Me2SO changed the substrate binding process more effectively (Km) than the rate of catalysis kcat..
2
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Influence of organic solvents on papain kinetics

100%
Szabelski M., Stachowiak K., Wiczk W.
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2001
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vol. 48
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issue 4
1197-1201
EN
Papain activity was studied in water-organic solvent mixtures using the fluorogenic substrate Dabcyl-Lys-Phe-Gly-Gly-Ala-Ala-Edans. The increase of organic solvent (MeOH, EtOH, iPrOH, TFE, MeCN, (MeO)2Et and DMF) concentration in the mixture caused a substantial decrease the initial rate of papain-catalyzed hydrolysis. Moreover, the number of papain active sites decreased with the increase of DMF and MeOH concentration.
3
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Fluorescent chemosensors for metal ions based on 3-(2-benzoxazol-5-yl)alanine skeleton

100%
Milewska M., Guzow K., Wiczk W.
Open Chemistry
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2010
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vol. 8
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issue 3
674-686
EN
The ability of new chelate ligands, benzoxazol-5-yl-alanine derivatives substituted in position 2 by heteroaromatic substituent, to form complexes with selected metal ions in acetonitrile are studied by means of absorption and steady-state and time-resolved fluorescence spectroscopy. Among the ligands studied, only azaaromatic derivatives form stable complexes with transition metal ions in the ground state. Their absorption bands are bathochromically shifted enabling to use those ligands as ratiometric sensors. The fluorescence of each ligand is quenched by metal ions, however, in the presence of Cd(II) and Zn(II) ions a new red shifted emission band is observed. [...]
4
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Influence of amino acid sequence on the interaction of short peptides containing 3-[2-(9-anthryl)benzoxazol-5-yl]-alanine with β-cyclodextrin

100%
Mrozek J., Guzow K., Sikorska E., Wiczk W.
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EN
The influence of peptide sequence and Leu chirality in linear and cyclic peptides containing 3-[2-(9-anthryl)benzoxazol-5-yl]alanine on interaction with β-cyclodextrin were studied using fluorescence and NMR spectroscopy. The analysis of enthalpy-entropy compensation effect (α=1.05±0.02 and TΔS00=15.1±0.5 kJ mol−1) indicates that the entropic contribution connected with the solvent reorganization is the major factor governing the peptides-β-cyclodextrin complexation. Moreover, spatial orientation of guest-host molecule depends more than association constant on Leu residue configuration. However, the cyclization of the peptide chain substantially decrease the association constant with β-CD. An analysis of 2D NMR spectra reveals that inclusion complex is formed by penetration of cyclodextrin cavity from wider and narrow rims by anthryl group in the case of Box(Ant)-SPKL or anthryl and Leu residues for Box(Ant)-SPK(D)L analogue. [...]
5
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Fluorescence resonance energy transfer in studies of inter-chrornophoric distances in biornolecules

100%
Lankiewicz L., Malicka J., Wiczk W.
Acta Biochimica Polonica
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1997
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vol. 44
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issue 3
477-489
6
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Fluorogenic peptide substrates for carboxydipeptidase activity of cathepsin B.

88%
Stachowiak K., Tokmina M., Karpińska A., Sosnowska R., Wiczk W.
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vol. 51
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issue 1
81-92
EN
Cathepsin B is a lysosomal cysteine protease exhibiting mainly dipeptidyl carboxypeptidase activity, which decreases dramatically above pH 5.5, when the enzyme starts acting as an endopeptidase. Since the common cathepsin B assays are performed at pH 6 and do not distinguish between these activities, we synthesized a series of peptide substrates specifically designed for the carboxydipeptidase activity of cathepsin B. The amino-acid sequences of the P5-P1 part of these substrates were based on the binding fragments of cystatin C and cystatin SA, the natural reversible inhibitors of papain-like cysteine protease. The sequences of the P'1-P'2 dipeptide fragments of the substrates were chosen on the basis of the specificity of the S'1-S'2 sites of the cathepsin B catalytic cleft. The rates of hydrolysis by cathepsin B and papain, the archetypal cysteine protease, were monitored by a continuous fluorescence assay based on internal resonance energy transfer from an Edans to a Dabcyl group. The fluorescence energy donor and acceptor were attached to the C- and the N-terminal amino-acid residues, respectively. The kinetics of hydrolysis followed the Michaelis-Menten model. Out of all the examined peptides Dabcyl-R-L-V-G-F- E(Edans) turned out to be a very good substrate for both papain and cathepsin B at both pH 6 and pH 5. The replacement of Glu by Asp turned this peptide into an exclusive substrate for cathepsin B not hydrolyzed by papain. The substitution of Phe by Nal in the original substrate caused an increase of the specificity constant for cathepsin B at pH 5, and a significant decrease at pH 6. The results of kinetic studies also suggest that Arg in position P4 is not important for the exopeptidase activity of cathepsin B, and that introducing Glu in place of Val in position P2 causes an increase of the substrate preference towards this activity.
7
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Fluorescence decay time distribution analysis of cyclic enkephalin analogues. Influence of the solvents and configuration of amino acids in position 2 and 3 on changes in conformation

88%
Malicka J., Groth M., Czaplewski C., Liwo A., Wiczk W.
Acta Biochimica Polonica
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1999
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vol. 46
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issue 3
615-629
8
Content available remote

Fluorescence decay time distribution analysis of cyclic enkephalin analogues; Influence of solvent and Leu configuration in position 5 on conformation

76%
Malicka J., Ganzynkowicz R., Groth M., Czaplewski C., Karolczak J., Liwo A., Wiczk W.
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2001
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vol. 48
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issue 1
95-102
EN
Lifetime distribution analysis were performed to study the influence of Leu configuration in position 5 on changes of the peptide chain of cyclic analogues of enkephalins containing a fluorescence donor and acceptor in different solvents. The configuration change of Leu5 in all the analogues of enkephalins studied which contain donor-acceptor pairs has no apparent influence on Trp lifetime distributions. In contrast, there is a significant solvent effect on the shape of lifetime distribution.
9
Content available remote

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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