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Soft Matter Sep 2022The α-helix has a significant role in protein function and structure because of its rigidity. In this study, we investigate the persistence length, , of α-helical...
The α-helix has a significant role in protein function and structure because of its rigidity. In this study, we investigate the persistence length, , of α-helical poly-L-lysine, PLL, for two molecular weights. PLL experiences a random coil-helix transition as the pH is raised from 7 to 12. Using light scattering experiments to determine the radius of gyration (), hydrodynamic radius, (), the shape factor (/), and second virial coefficient (), and circular dichroism to determine the helical content, we find the structure and of PLL as a function of pH (7.4-11.4) and ionic strength (100-166 mM). With increasing pH, we find an increase in from 2 nm to 15-21 nm because of α-helix formation. We performed dissipative particle dynamics (DPD) simulations and found a similar increase in . While this is less than that predicted by molecular dynamics simulations, it is consistent with other experimental results, which quantify the mechanics of α-helices. By determining the mechanics of helical polypeptides like PLL, we can further understand their implications to protein function.
Topics: Circular Dichroism; Molecular Weight; Peptides; Polylysine; Protein Conformation, alpha-Helical
PubMed: 36039676
DOI: 10.1039/d2sm00921h -
International Journal of Biological... Dec 2023To address the environmental and food contamination issues caused by plastics and microorganisms, antimicrobial films using natural polymers has attracted enormous...
To address the environmental and food contamination issues caused by plastics and microorganisms, antimicrobial films using natural polymers has attracted enormous attention. In this work, we proposed a green, convenient and fast approach to prepare antimicrobial films from chitosan (CS), bacterial cellulose (BC) and ε-polylysine (ε-PL). The effects of different concentrations of ε-PL (0 %, 0.25 %, 0.5 %, 0.75 %, 1 %, w/v) on the physicochemical properties and antibacterial activity of composite films (CS-DABC-x%PL) were systematically investigated. Furthermore, a comprehensive comparison with purely physically mixed CS-BC-x%PL films provides a deeper understanding of the subject matter. Characterization tests of the films were conducted using scanning electron microscope (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results suggested that the incorporation of 0.5 % ε-PL reduced the water solubility of the composite film by 19.82 %, along with improved the tensile strength and thermal stability by 37.31 % and 28.54 %. As ε-PL concentration increased to 1 %, the antibacterial performance of the films gradually enhanced. Additionally, the CS-DABC-0.5%PL film demonstrated effectiveness in delaying the deterioration of tilapia. These findings imply that this novel green packaging material holds significant potential in food preservation due to its promising antibacterial properties.
Topics: Chitosan; Cellulose; Polylysine; Food Packaging; Anti-Bacterial Agents; Anti-Infective Agents; Food Preservation
PubMed: 37804899
DOI: 10.1016/j.ijbiomac.2023.127231 -
Microbial Cell Factories Oct 2022ε-poly-L-lysine (ε-PL) is the main secondary metabolite of Streptomyces albulus, and it is widely used in the food industry. Polylysine synthetase (Pls) is the last...
ε-poly-L-lysine (ε-PL) is the main secondary metabolite of Streptomyces albulus, and it is widely used in the food industry. Polylysine synthetase (Pls) is the last enzyme in the ε-PL biosynthetic pathway. Our previous study revealed that Pls overexpressed in S. albulus CICC11022 result in the efficient production of ε-PL. In this study, a Pls gene knockout strain was initially constructed. Then, genomic, transcriptomic and metabolomic approaches were integrated to study the effects of the high expression and knockout of Pls on the gene expression and metabolite synthesis of S. albulus. The high expression of Pls resulted in 598 significantly differentially expressed genes (DEGs) and 425 known differential metabolites, whereas the inactivation of Pls resulted in 868 significant DEGs and 374 known differential metabolites. The expressions of 8 and 35 genes were negatively and positively associated with the Pls expression, respectively. Subsequently, the influence mechanism of the high expression and inactivation of Pls on the ε-PL biosynthetic pathway was elucidated. Twelve metabolites with 30% decreased yield in the high-expression strain of Pls but 30% increased production in the Pls knockout strain were identified. These results demonstrate the influence of Pls on the metabolism of S. albulus. The present work can provide the theoretical basis for improving the production capacity of ε-PL by means of metabolic engineering or developing bioactive substances derived from S. albulus.
Topics: Polylysine; Transcriptome; Ligases; Streptomyces; Fermentation
PubMed: 36307825
DOI: 10.1186/s12934-022-01953-8 -
Molecules (Basel, Switzerland) Apr 2019We developed a tumor-targeted contrast agent based on linear polylysine (PLL) by conjugating a small molecular imaging agent, fluorescent molecule and targeting agent...
We developed a tumor-targeted contrast agent based on linear polylysine (PLL) by conjugating a small molecular imaging agent, fluorescent molecule and targeting agent amino phenylboronic acid onto the amino groups of polylysine, which can specifically target monosaccharide sialic acid residues overexpressing on the surface of tumor cell membranes. Further, 3,4,5,6-Tetrahydrophthalic anhydride (DCA) was attached to the free amino groups of the polylysine to change to a negative charge at physiology pH to lower the cytotoxicity, but it soon regenerated to a positive charge again once reaching the acidic intratumoral environment and therefore increased cell uptake. Laser confocal microscopy images showed that most of the polymeric contrast agents were bound to the cancer cell membrane. Moreover, the tumor targeting contrast agent showed the same magnetic resonance imaging (MRI) contrasting performance in vitro as the small molecule contrast agent used in clinic, which made it a promising tumor-targeting polymeric contrast agent for cancer diagnosis.
Topics: Animals; Contrast Media; Dogs; Hep G2 Cells; Humans; Madin Darby Canine Kidney Cells; Magnetic Resonance Imaging; Microscopy, Confocal; Neoplasms; Polylysine
PubMed: 30991689
DOI: 10.3390/molecules24081477 -
Protein Science : a Publication of the... Jul 2021Biomolecular condensates assembled through liquid-liquid phase separation (LLPS) of proteins and RNAs are currently recognized to play an important role in cellular...
Biomolecular condensates assembled through liquid-liquid phase separation (LLPS) of proteins and RNAs are currently recognized to play an important role in cellular organization. Their assembly depends on the formation of a network of transient, multivalent interactions between flexible scaffold biomolecules. Understanding how protein and RNA sequences determine these interactions and ultimately regulate the phase separation is an open key challenge. Recent in vitro studies have revealed that arginine and lysine residues, which are enriched in most cellular condensates, have markedly distinct propensities to drive the LLPS of protein/RNA mixtures. Here, we employ explicit-solvent atomistic molecular dynamics simulations to shed light on the microscopic origin of this difference by investigating mixtures of polyU oligonucleotides with either polyR/polyK peptides. In agreement with experiments, our simulations indicate that arginine has a higher affinity for polyU than lysine both in highly diluted conditions and in concentrated solutions with a biomolecular density comparable to cellular condensate. The analysis of intermolecular contacts suggests that this differential behavior is due to the propensity of arginine side chains to simultaneously form a higher number of specific interactions with oligonucleotides, including hydrogen bonds and stacking interactions. Our results provide a molecular description of how the multivalency of the guanidinium group enables the coordination of multiple RNA groups by a single arginine residue, thus ultimately stabilizing protein/RNA condensates.
Topics: Peptides; Poly U; Polylysine; RNA
PubMed: 33982350
DOI: 10.1002/pro.4109 -
Journal of Controlled Release :... Aug 2013PEI and polylysine are among the most investigated synthetic polymeric carriers for DNA delivery. Apart from their practical use, these 2 classes of polymers are also of... (Comparative Study)
Comparative Study
PEI and polylysine are among the most investigated synthetic polymeric carriers for DNA delivery. Apart from their practical use, these 2 classes of polymers are also of interest from a fundamental point of view as they both can be prepared in different architectures (linear and branched/dendritic) and in a wide range of molecular weights, which is attractive to establish basic structure-activity relationships. This manuscript reports the results of an extensive study on the influence of molecular weight and architecture of a library of polylysine variants that includes linear, dendritic and hyperbranched polylysine. Hyperbranched polylysine is a new polylysine-based carrier that is structurally related to dendritic polylysine but possesses a randomly branched structure. Hyperbranched polylysine is attractive as it can be prepared in a one-step process on a large scale. The performance of these 3 classes of polylysine analogs was evaluated by assessing eGFP and IgG production in transient gene expression experiments with CHO DG44 cells, which revealed that protein production generally increased with increasing molecular weight and that at comparable molecular weight, the hyperbranched analogs were superior as compared to the dendritic and linear polylysines. To understand the differences between the gene delivery properties of the hyperbranched polylysine analogs on the one hand and the dendritic and linear polylysines on the other hand, the uptake and trafficking of the corresponding polyplexes were investigated. These experiments allowed us to identify (i) polyplex-external cell membrane binding, (ii) free, unbound polylysine coexisting with polyplexes as well as (iii) polymer buffer capacity as three possible factors that may contribute to the superior transfection properties of the hyperbranched polylysines as compared to their linear and dendritic analogs. Altogether, the results of this study indicate that hyperbranched polylysine is an interesting, alternative synthetic gene carrier. Hyperbranched polylysine can be produced at low costs and in large quantities, is partially biodegradable, which may help to prevent cumulative cytotoxicity, and possesses transfection properties that can approach those of PEI.
Topics: Animals; CHO Cells; Cricetinae; Cricetulus; DNA; Dendrimers; Green Fluorescent Proteins; Immunoglobulin G; Polylysine; Transfection
PubMed: 23379996
DOI: 10.1016/j.jconrel.2013.01.019 -
Biophysical Journal Dec 2001The interaction of three polylysines, Lys(5) (N = 5), Lys(30) (N = 30), and Lys(100) (N = 100), where N is the number of lysine residues per chain, with...
The interaction of three polylysines, Lys(5) (N = 5), Lys(30) (N = 30), and Lys(100) (N = 100), where N is the number of lysine residues per chain, with phosphatidylserine-containing lipid bilayer membranes was investigated using 2H NMR spectroscopy. Lys(30) and Lys(100) added to multilamellar vesicles composed of (70:30) (mol:mol) mixtures of choline-deuterated 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) + 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoserine (POPS) produced two resolvable 2H NMR spectral components under conditions of low ionic strength and for cases where the global anionic lipid charge was in excess over the global cationic polypeptide charge. The intensities and quadrupolar splittings of the two spectral components were consistent with the existence of polylysine-bound domains enriched in POPS, in coexistence with polylysine-free domains depleted in POPS. Lys(5), however, yielded no 2H NMR resolvable domains. Increasing ionic strength caused domains to become diffuse and eventually dissipate entirely. At physiological salt concentrations, only Lys(100) yielded 2H NMR-resolvable domains. Therefore, under physiological conditions of ionic strength, pH, and anionic lipid bilayer content, and in the absence of other, e.g., hydrophobic, contributions to the binding free energy, the minimum number of lysine residues sufficient to produce spectroscopically resolvable POPS-enriched domains on the 2H NMR millisecond timescale may be fewer than 100, but is certainly greater than 30.
Topics: Hydrogen-Ion Concentration; Ions; Lipid Bilayers; Lysine; Magnetic Resonance Spectroscopy; Phosphatidylcholines; Phosphatidylglycerols; Phosphatidylserines; Polylysine; Protein Structure, Tertiary
PubMed: 11720998
DOI: 10.1016/S0006-3495(01)75968-1 -
Food Chemistry Oct 2022The present study mainly examines the effects of molecular weight of dextran on the reaction rate and functional characteristics between ε-polylysine (PL) and dextran....
The present study mainly examines the effects of molecular weight of dextran on the reaction rate and functional characteristics between ε-polylysine (PL) and dextran. The reaction kinetics, grafting degree and gel permeation chromatography are employed to evaluate the reaction rate and extent of these lard reaction. We find low activation energy (E) values that indicate that dextran with high molecular weight (HMD) exhibits a higher reaction rate with PL than that that of dextran with middle molecular weight (MMD) and low molecular weight (LMD). As for the functional characteristics of the formed conjugate, the conjugate of PL-HMD possesses a higher emulsifying activity, and PL-LMD exhibits higher antimicrobial activity than other molecular weight of dextran. We observe that long heating time at high temperatures can induce the partial degradation of the formed conjugates, which is reflected in the decreasing of the emulsifying and antimicrobial activity of PL-dextran conjugates.
Topics: Anti-Infective Agents; Dextrans; Maillard Reaction; Molecular Weight; Polylysine
PubMed: 35584577
DOI: 10.1016/j.foodchem.2022.133212 -
Cellular and Molecular Life Sciences :... Dec 2002Retrovirus-derived vectors are currently the preferred vectors used for human gene therapy protocols. Serious safety concerns persist, however, which are specifically...
Retrovirus-derived vectors are currently the preferred vectors used for human gene therapy protocols. Serious safety concerns persist, however, which are specifically related to the formation of a replication-competent virus, and no synthesis method currently employed precludes its formation with certainty. For many cell types, a low transduction efficiency results in insufficient therapeutic benefit. We describe the development of a molecular conjugate system, which permits transient chemical modification of a retrovirus with polylysine. This modification not only introduces additional safety features over standard unmodified retrovirus vectors, but also provides enhanced transduction efficiency.
Topics: Animals; Genetic Therapy; Genetic Vectors; Humans; Polylysine; Retroviridae; Transduction, Genetic
PubMed: 12568334
DOI: 10.1007/s000180200008 -
The Journal of Biological Chemistry Sep 1991The effects of cationic polyamino acids on insulin binding to soluble insulin receptor preparations were studied. Incubation of partially or fully purified receptor...
The effects of cationic polyamino acids on insulin binding to soluble insulin receptor preparations were studied. Incubation of partially or fully purified receptor preparations with polylysine (pLys) increased by several-fold the amount of [125I]insulin that remained associated with the receptor, as determined both by precipitation of receptor-insulin complexes by polyethylene glycol or by separation of the complexes from the free hormone by gel filtration. This elevation in the amount of bound insulin resulted from increased number of insulin binding sites, and could not be attributed to an increased affinity of the receptors to insulin. In fact, pLys reduced 2-3-fold the affinity of insulin binding to its receptor as determined by equilibrium binding studies, and by monitoring the rate of exchange of bound [125I]insulin with unlabeled hormone. pLys induced specific interactions between insulin and its native receptor since other basic compounds such as histone, spermidine, polymixin B, compound 48/80, lysine, and arginine failed to reproduce its effects. pLys did not interact with the free ligand, nor did it promote interactions between insulin and denatured receptor forms. Furthermore, pLys did not induce binding of insulin to other proteins present in the partially purified receptor preparations. The effects of pLys were time and dose-dependent and were proportional to the pLys chain length. The longer the chain, the greater was the effect. Enhanced insulin binding and receptor beta-subunit autophosphorylation (in the presence of insulin) exhibited a similar dependency on the chain length of pLys. pLys effects on insulin binding were associated with formation of large protein aggregates that remained trapped at the top of Sephacryl S-300 columns. These aggregates contained substantial amounts of receptor-insulin complexes. Our results suggest that pLys induces formation of receptor clusters that create de novo insulin binding sites among adjacent receptor tetramers. Alternatively, formation of receptor aggregates might facilitate insulin binding to a soluble receptor subfraction that otherwise fails to bind the hormone.
Topics: Animals; Binding Sites; Chemical Precipitation; Insulin; Kinetics; Peptides; Phosphorylation; Polylysine; Rats; Receptor Aggregation; Receptor, Insulin; Solubility; Wheat Germ Agglutinins
PubMed: 1894624
DOI: No ID Found