L-lysine Solution Research Articles

Injection of l-arginine or l-lysine before freezing delays the emulsifying and gelling properties deterioration of myofibrillar proteins of frozen porcine Longissimus lumborum muscle.

This study aimed to investigate the effects of injecting l-arginine and l-lysine solution before freezing and after thawing on the emulsifying and gelling properties of myofibrillar proteins (MPs) of frozen porcine longissimus dorsi. The results showed that the pre-freezing injections were more effective in alleviating the decrease in emulsifying properties of MPs compared with the post-thawing injections, as evidenced by higher emulsion creaming index, oil droplet size, interfacial absorptive protein amount, and viscoelasticity. Additionally, the pre-freezing injections could effectively mitigate the damage to the gelling properties of MPs, as evidenced by the formation of a homogeneous and compact gel network with stronger water retention, strength and chemical forces, as well as a higher proportion of non-flowing water, whereas the post-thawing injections could not. These results demonstrated that the injection of l-arginine and l-lysine solution before freezing could delay freezing-induced damage to the emulsifying and gelling properties of MPs, keeping the processing characteristics of frozen porcine.

Femtosecond laser synthesis and comparative analysis of fluorescent carbon dots from L-lysine aqueous solution

Laser synthesis of fluorescent species from biomolecules in living cells and tissues offers unique capabilities for fluorescent bioimaging, yet little is known about its mechanisms and characteristics of products. We examine synthesis of fluorescent products from water solution of L-lysine upon irradiation by trains of femtosecond laser pulses with varying parameters. We demonstrate that irradiation products contain nanoscale carbon-based fluorescent particles (carbon dots) with multi-colour and excitation-dependent emission. Morphology, chemical composition and fluorescent characteristics of irradiation products strongly depend on laser pulses parameters.

Improving quality attributes of refrigerated prepared pork chops by injecting l-arginine and l-lysine solution

This study investigated the effects of l-arginine and l-lysine, as well as storage duration, on the physicochemical properties, microstructure, protein oxidation, and sensory quality of prepared pork chops. The results indicated that 0.4 g/100 g l-arginine or 0.4 g/100 g l-lysine increased the pHs from 5.25 to 6.27 and 6.26, moisture content from 74.20 g/100 g–75.47 g/100 g and 75.47 g/100 g, and redness (a*) from 5.11 to 12.4 and 14.0 of uncooked pork chops, but decreased the purge loss from 2.5% to 1.07% and 1.08%, lightness (L*) from 61.7 to 46.9 and 46.8, and yellowness (b*) from 47.2 to 43.2, 45.6 of uncooked pork chops, cooking loss from 30.77% to 24.86% and 25.27% and shear force from 35.46 N to 21.84 N and 22.03 N, but enhanced the total acceptability of cooked pork chops relative to those of the control, respectively. Histological observation revealed that l-arginine or l-lysine caused the swelling of muscle fibers. l-Arginine and l-lysine could also effectively decrease total volatile basic nitrogen over a short period and inhibit protein oxidation during the entire refrigeration storage. The results suggested that l-arginine and l-lysine could potentially improve the quality attributes of prepared pork chops.

Quality of frozen porcine Longissimus lumborum muscles injected with l-arginine and l-lysine solution

This study investigated the effects of l-arginine and l-lysine on the water holding capacity, shear force, color, and protein denaturation of frozen porcine Longissimus lumborum. Four batches were prepared, each corresponding to samples of an experimental treatment: without a cryoprotective solution, injecting a 0.3% sodium tripolyphosphate and 0.5% NaCl solution, a 0.5% l-arginine solution, or a 0.5% l-lysine solution. The results showed that both l-arginine and l-lysine decreased thawing loss, cooking loss, shear force, L⁎ values, b⁎ values, and surface hydrophobicity, but they increased pH values, a⁎ values, percentages of peak areas for T21 relaxation times, and Ca2+-ATPase activity. Additionally, both histological and transmission electron microscopy images showed that l-lysine, and especially l-arginine could inhibit the formation of gaps between fiber bundles, alleviate the disruption of intracellular spaces, and maintain the structural integrity of sarcomeres. Overall, the results showed that both l-arginine and l-lysine hindered the structural damage of muscle fibers during freezing and protected myofibrillar proteins from denaturation, ultimately contributing to superior quality attributes.

Characterization of a Whole-Cell Biotransformation Using a Constitutive Lysine Decarboxylase from Escherichia coli for the High-Level Production of Cadaverine from Industrial Grade L-Lysine.

Cadaverine is used for the synthesis of the novel bio-polyamides 54, 56, and 510. Here, we examine the feasibility of using a lysine decarboxylase (LdcC) from Escherichia coli for high-level production of cadaverine. After sequential optimization of whole-cell biotransformation conditions, recombinant E. coli-overexpressing LdcC (EcLdcC) could produce 1.0M cadaverine from 1.2M crude L-lysine solution after 9h. EcLdcC retained a higher cadaverine yield after being reused 10 times at acidic and alkaline pH values than that of a recombinant E. coli strain overexpressing an inducible lysine decarboxylase (CadA), a conventional cadaverine producer (90 vs. 51% at pH6 and 55 vs. 15% at pH8). This study reveals that EcLdcC is a promising whole-cell biocatalyst for the bio-based production of cadaverine from industrial grade L-lysine in comparison to EcCadA.

Mutual diffusion coefficients of l-lysine in aqueous solutions

Mutual diffusion coefficients, D, were determined for aqueous solutions of l-lysine at T=298.15K at concentrations from (0.001 to 0.100)mol·dm−3. From these experimental results, the hydrodynamic radius Rh, diffusion coefficients at infinite dilution D0, the thermodynamic factors and activity coefficients γ, by using the Hartley equation, have been estimated, permitting us to have a better understanding of the thermodynamic of these systems of l-lysine in aqueous solutions.

Dynamics of supercooled water in a biological model system of the amino acid L-lysine.

The dynamics of supercooled water in aqueous solutions of the single amino acid L-lysine has been studied by broadband dielectric spectroscopy. The chosen biological system is unique in the sense that the water content is high enough to fully dissolve the amino acid, but low enough to avoid crystallisation to ice at any temperature. This is not possible to achieve for proteins or other larger biomolecules, where either hydrated samples without ice or solutions with large quantities of ice, or a cryoprotectant sugar, have to be studied at low temperatures. Thus, it is a key finding to be able to study water and biomolecular dynamics in a non-crystallized and biologically realistic solution at supercooled temperatures. Here, we focus on the water dynamics in this unique biological solution of L-lysine and water. We show that this unique system also gives rise to unique water dynamics, since, for the first time, a continuation of a cooperative (α-like) water relaxation is observed after a crossover to a more local β-like water relaxation has occurred with decreasing temperature. This implies that the supercooled water in the biological solution shows a twofold relaxation behaviour, with one relaxation identical to the main relaxation of water in hard confinements and one relaxation almost identical to the main water relaxation in ordinary aqueous solutions.

Growth stimulation of Microcystis aeruginosa by a bacterium from hyper-eutrophic water (Taihu Lake, China)

Cyanobacteria are the causative organisms of the algal blooms that occur in Taihu Lake. Dissolved organic nitrogen (DON) comprises a significant composition of nitrogen (N) pool in the water and may increase the nutrient source of microalgae. In the present study, we investigated the relationship between Microcystis aeruginosa, Pseudomonas sp. A3CT isolated from Taihu, and DON compounds. Co-incubation (3 days) of the bacterium with six DON compounds (four free amino acids and two combined amino acids) was collected as six decomposed DON solutions. The decomposed DON solutions of six compounds were used to test the stimulatory effect of nutrient regeneration by the bacterium. The growth of M. aeruginosa was significantly enhanced by the six decomposed DON solutions. M. aeruginosa grew much better under the six decomposed DON solutions than the corresponding undigested DON forms. Especially, the decomposed l-lysine solution, not only avoided the inhibiting effect of lysine on M. aeruginosa, but significantly promoted the cyanobacterial growth. Further chemical tests indicated that A3CT transformed DON into NH4+, which was utilized by M. aeruginosa. These results demonstrate that the bacterium plays an important role in decomposing unavailable DON forms into available NH4+, which suggests that the bacterium contributes to the fast growth of M. aeruginosa. Moreover, this phenomenon, in conjunction with previous studies, indicates that the responsible and effective way of harmful blooms is reducing the N and P inputs (including DON and DOP).

Effect of L-lysine in culture medium on nodule formation by bone marrow cells

The aim of this study was to estimate the effect of L-lysine on nodule formation by rat bone marrow cells in vitro. In this study, L-lysine was added to medium for mesenchymal stem cell culture to promote proliferation and differentiation of the cells, and then nodule formation was estimated in an in vitro rat bone marrow cell culture. Bone marrow cells from the bone shafts of the femora of Fischer 344 rats were cultured in minimum essential medium with 20 μl of L-lysine solution at 10﹣4, 10﹣5, 10﹣6, 10﹣7 or 10﹣8 M. Dexamethasone was also added to the medium at 10 nM for differentiation of stem cells from bone marrow into osteoblast progenitor cells. The subculture was performed for 2 weeks. The quantity of osteocalcin in rat bone marrow cell culture with dexamethasone was 392 ng/ml. In the medium with dexamethasone and 10﹣8 M L-lysine, the quantity of osteocalcin was 437 ng/ml. Nodules only formed upon addition of 20 μl of L-lysine at 10﹣8 M. It was indicated that 10﹣8 M L-lysine should be the optimal concentration for calcification. For nodule formation by rat bone marrow cells in vitro, the optimum concentration of L-lysine in culture medium might be 20 μl of 10﹣8 M. L-lysine could play an important role in matrix production for bone formation in vitro.

Semiorganic nonlinear optical l-lysine sulphate growth and characterization

L-lysine sulphate (LLS), a semiorganic nonlinear optical (NLO) material useful for frequency doubling in the IR region, has been synthesized. The solubility studies have been carried out in the temperature range 30-50 degrees C. Single crystals have been grown by slow evaporation method from an aqueous acetone solution of l-lysine and sulphuric acid. The grown crystals were bulk, bright and transparent. These crystals were characterized by X-ray and FTIR studies. Powder X-ray pattern indicates that LLS crystallizes in orthorhombic space group P2(1)2(1)2(1) with four unit cells. FTIR spectral studies were performed for the conformation of the l-lysine molecule and hydrogen bonds. The optical transmission spectra of the grown crystal are tested by UV-vis spectrophotometer and found that the crystal was transparent over entire visible region. The second harmonic generation test of the LLS revealed the nonlinear nature of the crystal.

Basic Amid Acid-Assisted Synthesis of Resorcinol−Formaldehyde Polymer and Carbon Nanospheres

Polymer nanospheres were synthesized through polymerization of resorcinol/formaldehyde (RF) in the presence of a basic amino acid, l-lysine, as a catalyst. The diameters of the RF polymer nanospheres can be tuned in the range of 30−650 nm by adjusting the molar ratios of l-lysine/H2O and resorcinol/H2O in the precursor solutions. The pH of l-lysine solution was reduced from 9.3 to 7.0 just after it was mixed with the RF solution, indicating that l-lysine molecules in the solution were consumed by interacting with resorcinol. As a result, particle growth rate extremely reduces. Thus, the particle size of the RF polymer was not much dependent with synthesis time. Thus, the use of l-lysine facilitates precise control of the size of the RF polymer nanospheres compared to the synthesis using an ammonia solution as a catalyst. Carbonized particles showed the same size as the RF polymer nanospheres. The resulting carbon nanospheres had mesopores and macropores with a surface area of 330−400 m2/g.

Silica Nanoparticle Crystals and Ordered Coatings Using Lys-Sil and a Novel Coating Device

Silica nanoparticles with a narrow particle size distribution and controlled diameters of 10-20 nm are synthesized via hydrolysis and hydrothermal aging of tetraethylorthosilicate in an aqueous L-lysine solution. Cryo-transmission electron microscopy (cryo-TEM) reveals that the silica nanoparticles assemble to form close-packed nanoparticle crystals over short length scales on carbon-coated grids. Evaporative drying of the same sols results in nanoparticle stability and remarkable long-range facile ordering of the silica nanoparticles over scales greater than 10 microm. Whereas small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) discount the possibility of a core (silica)-shell (lysine) structure, the possibility remains for lysine occlusion within the silica nanoparticles and concomitant hydrogen bonding effects driving self-assembly. Facile ordering of the silica nanoparticles into multilayer and monolayer coatings over square-centimeter areas by evaporation-induced self-assembly is demonstrated using a novel dip-coating device.

Optimization of the irradiation power in chemical exchange dependent saturation transfer experiments

In chemical exchange dependent saturation transfer imaging experiments, exchangeable solute protons are saturated and the transfer of saturation to water is subsequently detected. When the applied irradiation power is comparable to the resonance frequency difference between the water protons and saturated solute protons, the proton transfer (PT) efficiency is reduced due to concomitant direct saturation effects. In this study, the PT process is modeled using a two-pool system. An empirical general proton transfer ratio (PTR) equation for arbitrary RF irradiation power is derived, and its optimal power to maximize the PTR is analyzed. The results are confirmed experimentally on 4.7 T using a poly- l-lysine solution. The theory provides a useful tool for optimizing the irradiation power of the PT sequences in the presence of direct saturation effects.

Electrochemical measurement of phenothiazine-interacted DNA

The amount of DNA was measured by using thioridazine, which would be attached to the DNA, as an electrochemical indicator. An indicator (thioridazine) solution, a test solution (DNA solution), and a poly- l-lysine solution were successively placed on a glassy carbon electrode, and the electrode was allowed to dry; DNA was immobilized on an electrode surface by the electrostatic binding between DNA and poly- l-lysine. The electrode was immersed into a buffer solution for 15 min, and then differential pulse voltammetry (DPV) was carried out: the oxidation current peak of thioridazine was observed, and its magnitude depended on the amount of DNA in the solution which was used for preparing the electrode. It could be estimated between 0.2 μg DNA (corresponds to 630 pmol nucleotides) to 20 μg DNA (63 nmol nucleotides) from the oxidation peak current of DPV.

Assay system for tumor control effect using encapsulated multicellular spheroid models

Most advanced head and neck cancers are inoperable, hence they are treated by either radiotherapy or combined chemoradiotherapy. More effective methods of combined chemoradiotherapy are certainly required for improving the curability of these cancers. Numerous factors involved in modifying the effectiveness have to be quantitatively analyzed for improvement; this has been a limiting factor preventing therapeutic progress. The purpose of the present study was to establish an experimental technique for assessing the in vivo effect of radiotherapy or chemoradiotherapy on multicellular tumor spheroids encapsulated in a semitransparent microcapsule. Mouse squamous carcinoma cells suspended in sodium alginate solution were transferred to a syringe connected to an air jet apparatus. Droplets containing cells were dropped into a calcium chloride solution, which caused them to gel, and then treated with poly L-lysine solution. The encapsulated cells were cultured in vitro for three weeks to form multicellular spheroids with central necrosis. The spheroids were either X-irradiated in vitro or in vivo by grafting in a nude mouse. The dose-cell survival curve in vivo was biphasic with a radioresistant component which was not observed in vitro. This method was considered to be applicable to human tumor cells and useful for determining the effectiveness of therapeutic agent as human solid tumor models in vivo.

The characterization of liposomal glucose oxidase electrodes for the measurement of glucose

Many biosensors have been described for the measurement of glucose in order to monitor diabetic patients. Glucose oxidase has been used commonly in the construction of glucose sensors but the performance of this enzyme is limited by enzyme saturation kinetics, which restrict the measurement of clinically relevant glucose concentrations (0 to 25 mM). Diffusion limiting membranes have been described that result in the exposure of the enzyme to lower concentrations of glucose than are present in the bulk test solution. Recently a liposomal enzyme electrode was reported whereby glucose oxidase was encapsulated within liposomes so that the lipid bilayer was the diffusion limiting membrane. It was shown that the electrode response was defined by the lipid constituents of the liposome, and that a linear response to glucose could be achieved up to 40 mM. This paper describes research undertaken to improve the methods of production of a liposomal enzyme electrode. Improved immobilization of liposomes is demonstrated with the use of poly- l-lysine solution. The variation in electrode response with respect to the amount of glucose oxidase liposomally encapsulated is reported. The new method allows a greater number of sensors to be produced from a single batch of liposomes. Studies also show the biofouling effects of the lipid constituents of ruptured liposomes on the response of the electrode to glucose over time.

Influence of cinnamic acid on lymphocyte proliferation, cytokine release and Klebsiella infection in mice

The effect of a complex of propolis constituents, cinnamic acid and L-lysine, on host defence mechanisms was investigated. After intraperitoneal (ip) application of cinnamic acid lysine complex (CN.Ly) to mice at a dose of 3 mg/kg for 3 consecutive days prior to inoculation with Klebsiella pneumoniae, a protective effect was observed. The action of CN.Ly was associated with its ability to provoke proliferation of thymic and splenic lymphocytes and to augment mitogen-induced proliferation, and the release of interleukin-1 (IL-1) and interleukin-2 (IL-2). In all experiments, a solution of L-lysine in a concentration equivalent to the lysine content in the complex was used for comparison. The results indicated that free lysine acted in a mitogen-like manner predominantly on T-lymphocytes. In the complex, lysine played the role of a carrier and exhibited a less pronounced effect

Crystallization Control by Additives: Molecular Recognition. Application to the Determination Of L-Glutamic Acid Using L-Lysine as Substrate

Abstract The effects of 19 amino acids on the crystallization of L-Asparagine and L-Lysine have been comparatively studied with analytical purposes. A very simple nephelometric procedure is used for determination of L-Glutamic acid, based on its inhibitory action on the crystallization of L-Lysine. The obtention of supersaturated solutions of L-Lysine was accomplished by means of the change in the solvent composition. Thus, the addition of isopropanol to stable aqueous solutions of this amino acid, allows to obtain unstable supersaturated solutions. The method suffers from very few interferences. The method was also applied to the determination of L-Glutamic acid in pharmaceutical products.

Extraction of L-Lysine from Its Dilute Aqueous Solutions by Rotating Film Pertraction

Removal and concentration of L-lysine in a three liquid phase pertraction system was studied using a laboratory three stage rotating disk pertractor. A 5% (vol) solution of Di-2-ethyl hexyl phosphoric acid (D2EHPA) in normal paraffins was used as an intermediate membrane liquid. The amino acid was extracted from its dilute aqueous solution (feed F) and concentrated in the stripping liquid R—a 1N solution of HCl in water. D2EHPA dissolved in the membrane liquid played the role of a ion exchange carrier. It was found that the most important parameters controlling the efficiency of this continuous pertraction process are the speed of disk rotation and the feed solution flowrate. The counter-current flow arrangement in the apparatus and the high flowrate ratio chosen provided nearly complete removal of solute from the feed as well as a concentrated solution of L-lysine.

THE EFFECTS OF INTRAVENOUS INFUSION OF LYSINE, LYSINE PLUS METHIONINE OR CARNITINE ON PLASMA AMINO ACIDS AND MILK PRODUCTION OF DAIRY COWS

Four lactating Holstein cows were each infused intravenously for periods of up to 9 days with solutions of L-lysine (15 g/day), L-lysine plus D,L-methionine (15 + 10 g/day) D,L-carnitine (20 g/day) or physiological saline. The cows were fed a ration of 2 kg chopped hay (14.8% crude protein), corn silage ad libitum (8.0% crude protein) and a concentrate mixture (16.5% crude protein) (1 kg/3 kg milk). Daily digestible protein intake was 1.85 kg/cow or 87% of calculated (National Academy of Sciences – National Research Council) requirements. There was no significant effect of infusion treatment on intake of corn silage, milk yield and composition or digestibility of the ration. The efficiencies of conversion of dietary protein to milk protein were 38.4, 38.6, 36.6 and 37.8% and nitrogen balances were 6, −2, 8 and 5 g/day for saline, lysine, lysine plus methionine and carnitine infusions. The concentration of carnitine in the milk was greater when carnitine was infused but was unaffected by the infusion of lysine and methionine. Plasma lysine and methionine were increased when these amino acids were infused. On the basis of plasma amino acid patterns it was concluded that methionine, lysine and threonine were possibly the most limiting amino acids under the conditions of this experiment and that in combination with a less than adequate energy intake (i.e. 87% of calculated requirements), infusion of lysine and methionine failed to give a response in production.