Guanidium Chloride Research Articles

Extremely large Seebeck coefficient of gelatin methacryloyl (GelMA)-based thermogalvanic cells by the dual effect of ion-induced crystallization and nanochannel control

The quasi-solid state thermogalvanic cells (TGCs) have been extensively investigated due to their high Seebeck coefficient (S) and suitability for wearable power generation. However, the influence of hydrogel nanostructure on Seebeck coefficient remains underexplored. In this study, biocompatible TGCs based on gelatin methacryloyl (GelMA) are fabricated via a fast-photocrosslinking process. Moreover, guanidium chloride (GdmCl) salts are directly introduced into the TGCs to enhance the Seebeck coefficient via ion-induced crystallization in the p-type FeCN63−/FeCN64− redox system. Small angle X-ray scattering reveals controlled GelMA hydrogel mesh size adjusting the amount of GdmCl, leading to improved intermolecular interactions between the guanidium cations and GelMA polymer. The optimized p-type Seebeck coefficient reaches an unprecedented 21.6 mV K−1, which is the highest thus far reported in the context of the TGC system. Furthermore, a prototype wearable thermoelectric generator (TEG) with an output voltage of 1.6 V under a temperature difference (ΔT) of 9 °C is able to power an LED directly without requiring an additional voltage booster. In brief, the dual effect of ion-induced crystallization and nanochannel control substantially enhances the Seebeck coefficient of the TGC, thereby offering a promising strategy for enhancing the performance of low-grade thermal energy harvesting wearable TEGs.

Assessment of acute and repeated pulmonary toxicities of oligo(2-(2-ethoxy)ethoxyethyl guanidium chloride in mice.

Oligo(2-(2-ethoxy)ethoxyethyl guanidinium chloride (PGH) and polyhexamethyleneguanidine phosphate (PHMG-P) are cationic biocides containing a guanidine group. Direct exposure of the lungs to PHMG-P is known to induce pulmonary inflammation and fibrotic changes. Few studies have assessed the pulmonary toxicity of PGH, another member of the guanidine family. In this study, we assessed the acute and repeated toxicity of PGH and PHMG-P to compare the pathological progression induced by both chemicals. PGH (1.5mg/kg) or PHMG (0.6mg/kg) was instilled intratracheally to mice once or three times every 4days; subsequently, cytokine levels were quantified and a histopathological examination was performed. To verify the toxic mechanism of PGH, we quantified cell viability and cytokine production induced by PGH or PHMG-P in the presence or absence of anionic material in cells. Instillation of PGH and PHMG-P into the mouse lung increased cytokine production, immune cell infiltration, and pulmonary fibrotic changes. These pathological changes were exacerbated over time in the single- and the repeated-dose PHMG-P groups, but were resolved over time in the PGH groups. PGH or PHMG-P showed cytotoxic effects, IL-1β secretion, and ROS production in a dose-dependent manner in human cell lines. However, the co-treatment of anionic materials with PGH or PHMG-P significantly reduced these toxic responses, which confirmed that the cation of PGH disrupted the plasma membrane via ionic interaction, as observed for PHMG-P. In addition, we suggest the disruption of plasma membrane as a molecular initiating event of cationic chemicals-induced adverse outcomes when exposed directly to the lungs.

Fabrication of tunable anatase/rutile heterojunction N/TiO2 nanophotocatalyst for enhanced visible light degradation activity

With special focus of the effect of dopant concentration on physicochemical properties, a series of visible light active nitrogen doped titania (N/TiO2) nanomaterials were successfully synthesized via sol-gel method of titanium butoxide in the presence of benign N dopant guanidium chloride. The resulting anatase/rutile (A/R) mixed phase materials were subjected to different characterization techniques, and their photocatalytic performance was evaluated against methylene blue (MB) dye under visible light irradiation. The results confirmed that the N was effectively doped in interstitial sites (7.2 atomic%) with Ti-N-O linkage, and the N/Ti mol ratio significantly dictated the physicochemical properties, and photodegradation of the photocatalysts. Notably, the mesoporous N/TiO2 (1:1 N/Ti, 42% A, 58% R with 2.91 eV band gap energy) demonstrated 97% photodegradation activity along with a fastest photodegradation rate of 0.033 min−1, which was 17 times faster than the undoped TiO2. Such excellent improvement was attributed to the synergistic effect of N-doping and optimal A/R phase composition that led to higher light absorption capacity and specific surface area, lower band gap energy and recombination rate as well as higher interstitial N in the crystal. Such promising green heterojunction photocatalysts have a broad range of applications from photocatalysis to photovoltaics.

Protein stabilizer, NDSB-195, enhances the dynamics of the β4 -α2 loop of ubiquitin.

Non-detergent sulfobetaines (NDSBs) are a new group of small, synthetic protein stabilizers, which have advantages over classical compatible osmolytes, such as polyol, amines, and amino acids: they do not increase solution viscosity, unlike polyols, and they are zwitterionic at all pH ranges, unlike amines and amino acids. NDSBs also facilitate the crystallization and refolding of proteins. The mechanism whereby NDSBs exhibit such activities, however, remains elusive. To gain insight into this mechanism, we studied, using nuclear magnetic resonance (NMR), the effects of dimethylethylammonium propane sulfonate (NDSB-195) on the dynamics of ubiquitin, on which a wealth of information has been accumulated. By analyzing the line width of amide proton resonances and the transverse relaxation rates of nitrogen atoms, we found that NDSB-195 enhances the microsecond-millisecond dynamics of a β4 -α2 loop of ubiquitin. Although those compounds that enhance protein dynamics are generally considered to destabilize protein molecules, NDSB-195 enhanced the stability of ubiquitin against guanidium chloride denaturation. Thus, the simultaneous enhancement of stability and flexibility by a single compound can be attained.

Novel S-enantioselective lipase TALipB from Trichosporon asahii MSR54: Heterologous expression, characterization, conformational stability and homology modeling

A novel lipase encoding gene, TALipB from Trichosporon asahii MSR54 was heterologously expressed in Escherichia coli using three vectors, pET22b, pET28a & pEZZ18. The three recombinant proteins, viz. C-hexahistidine fused HLipB, N and C-hexahistidine fused HLipBH and ZZ-fused ZZLipB were purified using affinity chromatography. All the three enzymes were mid to long fatty acyl chain selective on p-NP esters and S-enantioselective irrespective of tags. HLipB had lowest activation energy (3.5Kcalmol−1) and highest catalytic efficiency (254mM−1min−1) on p-NP caprate followed by HLipBH and ZZLipB. However, ZZLipB demonstrated best pH stability (pH 6–10), thermostability (t1/2 of 50min at 70°C) and stability toward the denaturant Guanidium chloride (300mM). Far-UV CD and fluorescence studies confirmed the role of N-terminal ZZ-tag in stabilizing the protein by altering its secondary and tertiary structures. All the three proteins were thiol activated. ZZLipB required higher concentration of β-mercaptoethanol as compared to the other two proteins to attain similar velocity. This indicated the involvement of additional disulfide bonds in its conformational stability. In silico analysis suggested low sequence identity of the enzyme with the available database but a close structural homology with Candida antarctica lipase B (CALB) was revealed by PHYRE2. MULTALIN with CALB predicted the active site residues (Ser137–Asp228–His261) which were confirmed by superimposition and site directed mutagenesis.

Unfolding and Refolding Study of a Large Dimeric Protein β-Glucosidase from Almond Monitored by Fluorescence Spectroscopy.

In our present investigation, the unfolding and refolding of β-glucosidase (BGL-Al) from sweet almond was investigated using tryptophan (Trp) fluorescence spectroscopy. When the unfolding of BGL-Al was induced by guanidium chloride (GdnHCl) and monitored using biological activity as well as Trp fluorescence spectroscopic measurement, we observed that the denaturation of BGL-Al could be easily induced by low concentration of GdnHCl and the enzyme was completely inactivated at 1.0 M GdnHCl. Higher unfolding in the presence of reducing agent revealed that the protein perhaps containing multiple di-sulfide bonds indicating a reason of high stability against unfolding by GdnHCl. Refolding results suggested that the protein refolded with high yield from 1 M GdnHCl denatured state, however, refolded with negligible yield from completely unfolded state. The kinetic studies of BGL-Al refolding unravel a two phase refolding process with calculated t1/2 (refolding half time) of 1.8 and 33 min, respectively. When 8-Anilino-1-naphthalenesulfonic acid (ANS) was used as extrinsic fluorophore, we found that the surface hydrophobicity of BGL-Al was continuously decreased during GdnHCl-mediated unfolding. The surface hydrophobicity of the protein was calculated to be as high as 128.32. Acrylamide quenching study demonstrated that Trp residues of BGL-Al are mostly and hence they must be located either on the surface or in the crevices accessible by quenchers.

Complexity of the folding transition of the B domain of protein A revealed by the high-speed tracking of single-molecule fluorescence time series.

The equilibrium unfolding transition of the B domain of protein A (BdpA) was investigated by using single-molecule fluorescence spectroscopy based on line-confocal detection of fast-flowing samples. The method achieved the time resolution of 120 μs and the observation time of a few milliseconds in the single-molecule time-series measurements of fluorescence resonance energy transfer (FRET). Two samples of BdpA doubly labeled with donor and acceptor fluorophores, the first possessing fluorophores at residues 22 and 55 (sample 1) and the second at residues 5 and 55 (sample 2), were prepared. The equilibrium unfolding transition induced by guanidium chloride (GdmCl) was monitored by bulk measurements and demonstrated that the both samples obey the apparent two-state unfolding. In the absence of GdmCl, the single-molecule FRET measurements for the both samples showed a single peak assignable to the native state (N). The FRET efficiency for N shifts to lower values as the increase of GdmCl concentration, suggesting the swelling of the native state structure. At the higher concentration of GdmCl, the both samples convert to the unfolded state (U). Near the unfolding midpoint for sample 1, the kinetic exchange between N and U causes the averaging of the two states and the higher values of the relative fluctuation. The time series for different molecules in U showed slightly different FRET efficiencies, suggesting the apparent heterogeneity. Thus, the high-speed tracking of fluorescence signals from single molecules revealed a complexity and heterogeneity hidden in the apparent two-state behavior of protein folding.

Evidence of unfolded protein translocation through a protein nanopore.

Protein nanopores are mainly used to study transport, unfolding, intrinsically disordered proteins, protein-pore interactions, and protein-ligand complexes. This single-molecule sensor for biomedical and biotechnological applications is promising but until now direct proof of protein translocation through a narrow channel is lacking. Here, we report the translocation of a chimera molecule through the aerolysin nanopore in the presence of a denaturing agent, guanidium chloride (1.5 M) and KCl (1 M). The chimera molecule is composed of the recombinant MalE protein with a unique cysteine residue at the C-terminal position covalently linked to a single-stranded DNA oligonucleotide. Real-time polymerase chain reaction (PCR) was used to detect the presence of chimera molecules that have been effectively translocated from the cis to trans chamber of the set up. Comparing the electrical signature of the chimera related to the protein or oligonucleotide alone demonstrates that each type of molecule displays different dynamics in term of transport time, event frequency, and current blockade. This original approach provides the possibility to study protein translocation through different biological, artificial, and biomimetic nanopores or nanotubes. New future applications are now conceivable such as protein refolding at the nanopore exit, peptides and protein sequencing, and peptide characterization for diagnostics.

Synthesis of substituted 2-heteroarylbenzazol-5-ol derivatives as potential ligands for estrogen receptors

Exposure to estrogen is associated with increased risk of breast and other types of human cancer. One therapeutic goal would be the creation of new molecules that would retain hormonal potency while incorporating features to retard or prevent quinone toxicity. Hence, new structures closely related to ERB-041, a known ERβ selective agonist, were synthesized whereas the phenol ring is substituted with non-quinone forming rings such as pyrazole, 2-pyrimidine-2(1H)-one or pyridine-2(1H)-one. 2-Methyl-5-methoxy-1,3-benzoxazoles (or 1,3-benzothiazole) are key intermediates for the production of the pyrazole and pyrimidine-2(1H)-one analogs. The required 1,3-benzoxazoles were synthesized starting from reduction of 2-nitro-4-methoxyphenols, followed by condensation with trimethyl orthoacetate. Then, the diiminium perchlorate intermediates were prepared from the latter compounds by Vilsmeier–Haack reaction. The reaction of the resulting intermediates with hydrazine hydrate and guanidium chloride afforded the title pyrazole and pyrimidine-2(1H)-ones, respectively.The pyridine analogs were synthesized starting from the reaction of 2-amino-4-methoxyphenols with 6-bromopyridine-3-carboxaldehyde followed by oxidation with DDQ to afford bromopyridines. These compounds were next treated with benzyl alcohol in the presence of potassium tert-butoxide to afford 2-benzyloxypyridine, which in subsequent dealkylation with boron tribromide produced the title pyridine-2-(1H)-ones.

Unrecognized Bomb Hidden in the Babies' Room: Fatal Pulmonary Damage Related with Use of Biocide in Humidifiers

Unrecognized Bomb Hidden in the Babies' Room: Fatal Pulmonary Damage Related with Use of Biocide in Humidifiers

Engineered dimer interface mutants of triosephosphate isomerase: the role of inter-subunit interactions in enzyme function and stability

The role of inter-subunit interactions in maintaining optimal catalytic activity in triosephosphate isomerase (TIM) has been probed, using the Plasmodium falciparum enzyme as a model. Examination of subunit interface contacts in the crystal structures suggests that residue 75 (Thr, conserved) and residue 13 (Cys, variable) make the largest number of inter-subunit contacts. The mutants Cys13Asp (C13D) and Cys13Glu (C13E) have been constructed and display significant reduction in catalytic activity when compared with wild-type (WT) enzyme (∼ 7.4-fold decrease in k(cat) for the C13D and ∼ 3.3-fold for the C13E mutants). Analytical gel filtration demonstrates that the C13D mutant dissociates at concentrations <1.25 μM, whereas the WT and the C13E enzymes retain the dimeric structure. The order of stability of the mutants in the presence of chemical denaturants, like urea and guanidium chloride, is WT > Cys13Glu > Cys13Asp. Irreversible thermal precipitation temperatures follow the same order as well. Modeling studies establish that the Cys13Asp mutation is likely to cause a significantly greater structural perturbation than Cys13Glu. Analysis of sequence and structural data for TIMs from diverse sources suggests that residues 13 and 82 form a pair of proximal sites, in which a limited number of residue pairs may be accommodated.

High-recovery one-step purification of the DNA-binding protein Fur by mild guanidinium chloride treatment

Engineering of DNA-binding domains of regulatory proteins aimed to control gene expression requires a deep knowledge of protein–DNA interactions acquired from structural data on purified species. Most DNA-binding proteins work as dimers establishing multiple protein–protein contacts mainly driven by hydrophobic interactions, being its cleansing a difficult task because of solubility problems. One-step purification of soluble, functional recombinant FurA from the cyanobacterium Anabaena sp. PCC 7120 has been achieved using mild chaotropic conditions. FurA was isolated using a Zn-iminodiacetate chromatography of the crude extract obtained after sonication of Escherichia coli in the presence of 2 M guanidium chloride. CD and 1D NMR spectroscopies demonstrate that FurA conserves the native tertiary structure. Functional analysis reveals FurA ability to recognise and bind target DNAs. We propose that the use of chaotropic agents under mild denaturating conditions might have general application in the purification of DNA-binding proteins and other proteins prone to aggregation.

Purification and characterization of a wound-inducible thaumatin-like protein from the latex of Carica papaya

A 22.137 kDa protein constituent of fresh latex was isolated both from the latex of regularly damaged papaya trees and from a commercially available papain preparation. The protein was purified up to apparent homogeneity and was shown to be absent in the latex of papaya trees that had never been previously mechanically injured. This suggests that the protein belongs to pathogenesis-related protein family, as expected for several other protein constituents of papaya latex. The protein was identified as a thaumatin-like protein (class 5 of the pathogenesis-related proteins) on the basis of its partial amino acid sequence. By sequence analysis of the Carica genome, three different forms of thaumatin-like protein were identified, where the latex constituent belongs to a well-known form, allowing the molecular modeling of its spatial structure. The papaya latex thaumatin-like protein was further characterized. The protein appears to be stable in the pH interval from 2 to 10 and resistant to chemical denaturation by guanidium chloride, with a Δ G water 0 of 15.2 kcal/mol and to proteolysis by the four papaya cysteine proteinases. The physiological role of this protein is discussed.

The structural basis for peptide selection by the transport receptor OppA

Oligopeptide-binding protein A (OppA) from Lactococcus lactis binds peptides of an exceptionally wide range of lengths (4-35 residues), with no apparent sequence preference. Here, we present the crystal structures of OppA in the open- and closed-liganded conformations. The structures directly explain the protein's phenomenal promiscuity. A huge cavity allows binding of very long peptides, and a lack of constraints for the position of the N and C termini of the ligand is compatible with binding of peptides with varying lengths. Unexpectedly, the peptide's amino-acid composition (but not the exact sequence) appears to have a function in selection, with a preference for proline-rich peptides containing at least one isoleucine. These properties can be related to the physiology of the organism: L. lactis is auxotrophic for branched chain amino acids and favours proline-rich caseins as a source of amino acids. We propose a new mechanism for peptide selection based on amino-acid composition rather than sequence.

Unfolding and Folding Kinetics of Amyotrophic Lateral Sclerosis-Associated Mutant Cu,Zn Superoxide Dismutases

More than 110 mutations in dimeric, Cu,Zn superoxide dismutase (SOD) have been linked to the fatal neurodegenerative disease, amyotrophic lateral sclerosis (ALS). In both human patients and mouse model studies, protein misfolding has been implicated in disease pathogenesis. A central step in understanding the misfolding/aggregation mechanism of this protein is the elucidation of the folding pathway of SOD. Here we report a systematic analyses of unfolding and folding kinetics using single- and double-jump experiments as well as measurements as a function of guanidium chloride, protein, and metal concentration for fully metallated (holo) pseudo wild-type and ALS-associated mutant (E100G, G93R, G93A, and metal binding mutants G85R and H46R) SODs. The kinetic mechanism for holo SODs involves native dimer, monomer intermediate, and unfolded monomer, with variable metal dissociation from the monomeric states depending on solution conditions. The effects of the ALS mutations on the kinetics of the holoproteins in guanidium chloride are markedly different from those observed previously for acid-induced unfolding and for the unmetallated (apo) forms of the proteins. The mutations decrease the stability of holo SOD mainly by increasing unfolding rates, which is particularly pronounced for the metal-binding mutants, and have relatively smaller effects on the observed folding kinetics. Mutations also seem to favour increased formation of a Zn-free monomer intermediate, which has been implicated in the formation of toxic aggregates. The results reveal the kinetic basis for the extremely high stability of wild-type holo SOD and the possible consequences of kinetic changes for disease.

ADP Competes with FAD Binding in Putrescine Oxidase

Putrescine oxidase from Rhodococcus erythropolis NCIMB 11540 (PuO(Rh)) is a soluble homodimeric flavoprotein of 100 kDa, which catalyzes the oxidative deamination of putrescine and some other aliphatic amines. The initial characterization of PuO(Rh) uncovered an intriguing feature: the enzyme appeared to contain only one noncovalently bound FAD cofactor per dimer. Here we show that this low FAD/protein ratio is the result of tight binding of ADP, thereby competing with FAD binding. MS analysis revealed that the enzyme is isolated as a mixture of dimers containing two molecules of FAD, two molecules ADP, or one FAD and one ADP molecule. In addition, based on a structural model of PuO(Rh) that was built using the crystal structure of human monoamine oxidase B (MAO-B), we constructed an active mutant enzyme, PuO(Rh) A394C, that contains covalently bound FAD. These findings show that the covalent FAD-protein linkage can be formed autocatalytically and hint to a new-found rationale for covalent flavinylation: covalent flavinylation may have evolved to prevent binding of ADP or related cellular compounds, which would prohibit formation of flavinylated and functional enzyme.

Cloning, purification and comparative structural analysis of two hypothetical proteins from Mycobacterium tuberculosis found in the human granuloma during persistence and highly up-regulated under carbon-starvation conditions

Mycobacterium tuberculosis is a successful pathogen largely due to its ability to persist in humans while evading the host immune system. Rv2557 and Rv2558 are two uncharacterized proteins which have been found to be present in the human granuloma along with other important proteins like isocitrate lyase and nitric oxide reductase which are necessary for long-term persistence. The two proteins are up-regulated in in vitro carbon-starvation conditions designed to mimic the latent stage. Genes corresponding to Rv2557 and Rv2558 are found only in Mycobacterium sp. so far and share high sequence identity of 65.4% at the protein level. In the present study we have cloned and purified the proteins as part of a long-term goal to understand their functional roles and importance to the pathogen. We have probed for their biophysical properties. The proteins are monomeric and do not interact with each other as revealed by size-exclusion chromatography and pull-down assays. Circular dichroism experiments involving temperature and chemical denaturation studies demonstrate that Rv2557 is more structured compared to Rv2558, which is surprising, given the high sequence conservation between them. In fact the free energy change (Δ G 0) of Rv2557 during guanidium chloride induced denaturation is higher than Rv2558 indicating higher structural stability. The unfolding studies indicate that overall both proteins unfold in a cooperative two state process but adopt different modes of stabilization. The present work sets the stage for further experiments to probe the functions of the proteins.

Characterization of Pyridoxal 5'-Phosphate-Binding Domain and Folding Intermediate of Bacillus subtilis Serine Hydroxymethyltransferase: an Autonomous Folding Domain

The pyridoxal-5'-phosphate-binding domain (PLPbd) of bsSHMT (Bacillus subtilis serine hydroxymethyltransferase) was cloned and over-expressed in Escherichia coli. The recombinant protein was solublized, refolded and purified from inclusion bodies by rapid mixing followed by ion exchange chromatography. Structural and functional studies suggested the native form of the domain, which obtained as a monomer and had similar secondary and tertiary structural properties as when present in the bsSHMT. The domain also binds to the PLP however with slightly lesser affinity than the native enzyme. GdmCl (guanidium chloride)-induced equilibrium unfolding of the recombinant PLP-binding domain showed a single monophasic transition which corresponds with the second phase transition of the GdmCl-induced unfolding of bsSHMT. The results indicate that PLPbd of bsSHMT is an independent domain, which attains its tertiary structure before the dimerization of partially folded monomer and behaves as a single cooperative unfolding unit under equilibrium conditions.

Interleukin-6 (IL-6) and/or Soluble IL-6 Receptor Down-regulation of Human Type II Collagen Gene Expression in Articular Chondrocytes Requires a Decrease of Sp1·Sp3 Ratio and of the Binding Activity of Both Factors to the COL2A1 Promoter

Type II collagen is composed of alpha1(II) chains encoded by the COL2A1 gene. Alteration of this cartilage marker is a common feature of osteoarthritis. Interleukin-6 (IL-6) is a pro-inflammatory cytokine that needs a soluble form of receptor called sIL-6R to exert its effects in some cellular models. In that case, sIL-6R exerts agonistic action. This mechanism can make up for the partial or total absence of membrane-anchored IL-6 receptors in some cell types, such as chondrocytes. Our study shows that IL-6, sIL-6R, or both inhibit type II collagen production by rabbit articular chondrocytes through a transcriptional control. The cytokine and/or sIL-6R repress COL2A1 transcription by a -63/-35 sequence that binds Sp1.Sp3. Indeed, IL-6 and/or sIL-6R inhibit Sp1 and Sp3 expression and their binding activity to the 63-bp promoter. In chromatin immunoprecipitation experiments, IL-6.sIL-6R induced an increase in Sp3 recruitment to the detriment of Sp1. Knockdown of Sp1.Sp3 by small interference RNA and decoy strategies were found to prevent the IL-6- and/or sIL-6R-induced inhibition of COL2A1 transcription, indicating that each of these Sp proteins is required for down-regulation of the target gene and that a heterotypic Sp1.Sp3 complex is involved. Additionally, Sp1 was shown to interact with Sp3 and HDAC1. Indeed, overexpression of a full-length Sp3 cDNA blocked the Sp1 up-regulation of the 63-bp COL2A1 promoter activity, and by itself, inhibits COL2A1 transcription. We can conclude that IL-6, sIL-6R, or both in combination decrease both the Sp1.Sp3 ratio and DNA-binding activities, thus inhibiting COL2A1 transcription.

Dynamic Light Scattering Study of Self-Assembly of HPMA Hybrid Graft Copolymers

The time course of self-assembly of a hybrid hydrogel system was investigated using dynamic light scattering (DLS) techniques. The self-assembling system consisted of a hydrophilic synthetic N-(2-hydroxypropyl)methacrylamide (HPMA) polymer backbone and a pair of oppositely charged peptide grafts (CCE and CCK). These two distinct pentaheptad peptides were anticipated to act as physical cross-linkers by the formation of antiparallel coiled-coil heterodimers. Equimolar mixture of HPMA graft copolymers CCE-P and CCK-P solutions (where P is the HPMA copolymer backbone) with total concentration from 1.25 to 10 mg/mL were measured at a scattering angle 90 degrees and room temperature. A critical extension of average relaxation time was observed with increasing concentration and incubation time. To reveal the role of coiled-coil grafts in the self-assembly process, a pair of modified random coil peptides, CCEw and CCKy, was designed. The DLS evaluation of HPMA copolymer conjugates (CCEw-P and CCKy-P) at total concentration of 10 mg/mL demonstrated that no association occurred after 28 h of incubation. Moreover, addition of a competing peptide (CCK) or a denaturant (guanidium chloride, GndHCl) to the self-assembled CCE-P/CCK-P hydrogels resulted in partial disassembly or collapse of the hydrogel clusters. These results correlated to changes in the secondary structure of peptides (grafts) as measured by circular dichroism spectroscopy (CD). These investigations supported the hypothesis that the self-assembly of CCE-P/CCK-P into hybrid hydrogels is mediated by the formation of coiled-coil heterodimers.