Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We show with three proteins that trapping and release of the water molecules upon crystallization is a determinant of the crystallization thermodynamics. With HbC, a strong retrograde solubility dependence on temperature yields a high positive enthalpy of 155 kJ mol(-1), i.e., crystallization is only possible because of the huge entropy gain of 610 J mol(-1) x K(-1), stemming from the release of up to 10 water molecules per protein intermolecular contact. With apoferritin, the enthalpy of crystallization is close to zero. The main component in the crystallization driving force is the entropy gain due to the release upon crystallization of two water molecules bound to one protein molecules in solution. With both proteins, the density of the growth sites imaged by AFM is in excellent agreement with a calculation using the crystallization free energy. With lysozyme, the entropy effect due to the restructuring of the water molecules is negative. This leads to higher solubility.
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PMID:Solvent entropy contribution to the free energy of protein crystallization. 1235 72

Surface modification of MALDI probes is an attractive approach for combining bioaffinity isolation of targeted biomolecules with mass spectrometric analysis of the captured species. In this work, we demonstrate that a polymer thin film, produced by pulsed rf plasma polymerization of allylamine and deposited directly on a MALDI probe, can be subsequently biotinylated to develop a bioaffinity capture MALDI probe. The synthesis and characterization of the probe by XPS, FT-IR, and AFM is described, and the selective isolation of avidin from a three-component mixture of avidin, lysozyme, and cytochrome c is presented. These initial results offer encouragement for the further exploration of rf plasma polymer deposition as a novel approach for the development of on-probe affinity capture MALDI probes.
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PMID:Radio frequency plasma polymer coatings for affinity capture MALDI mass spectrometry. 1562 15

Surfaces based on grafted poly(2-methacryloyloxyethyl phosphorylcholine) (poly(MPC)) "brushes" with a constant graft density of 0.39 chain/nm2 and chain length from 5 to 200 monomer units were prepared by surface-initiated atom transfer radical polymerization (ATRP) on silicon wafers. The chain length and layer thickness of the poly(MPC) grafts were varied via the ratio of MPC to sacrificial initiator. The surfaces were characterized by water contact angle, XPS, and AFM. The effect of poly(MPC) chain length on fibrinogen and lysozyme adsorption was studied in TBS buffer at pH 7.4. The adsorption of both proteins on the poly(MPC)-grafted surfaces was greatly reduced compared to the unmodified silicon. Adsorption decreased with increasing chain length of the poly(MPC) grafts. Grafts of chain length 200 (MW 59 000) gave adsorption levels of 7 and 2 ng/cm2, respectively, for fibrinogen and lysozyme at 1 mg/mL protein concentration, corresponding to reductions of greater than 98% compared to the unmodified silicon. Adsorption experiments using mixtures of the two proteins showed that the suppression of protein adsorption on the poly(MPC)-grafted surfaces was not strongly dependent on protein size or charge.
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PMID:Adsorption of fibrinogen and lysozyme on silicon grafted with poly(2-methacryloyloxyethyl phosphorylcholine) via surface-initiated atom transfer radical polymerization. 1595 50

The mechanism of charge propagation in "ion channel sensors" (ICSs) consisting of gold electrodes modified with a layer of charged proteins and highly charged redox-active marker ions in solution was investigated by electrochemical techniques, QCM and AFM. The study is based on seven proteins (concanavalin A, cytochrome c, glucose oxidase, lysozyme, thyroglobulin, catalase, aldolase, and EF1-ATPase) in combination with seven electroactive marker ions ([Fe(CN)6]3-, [Fe(CN)6]4-, [Ru(NH3)6]3+, mono-, di-, and trimeric viologens), as well as a series of suppressor and enhancer ions leading to the following general statements: (i) electrostatic binding of charged marker ions to the domains of the protein is a prerequisite for an electrochemical current and (ii) charge propagation through the layer consists of electron hopping along surface-confined marker ions into the pores between adsorbed proteins. It is further shown that (iii) marker ions and suppressor ions with identical charge compete for oppositely charged sites on the protein domain, (iv) electrostatically bound multilayers of marker or enhancer ions with alternating charge form on a charged protein domain, and (v) self-exchange and exergonic ET catalysis between adsorbed marker ions and marker ions in solution take place. In addition to fundamental insight into the mechanism of charge propagation, valuable information for the design, optimization, and tailoring of new biosensors based on the ICS concept is demonstrated by the current findings.
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PMID:Charge propagation in "ion channel sensors" based on protein-modified electrodes and redox marker ions. 1608 79

This work examines physico-chemical properties influencing protein adsorption to anionic PLG microparticles and demonstrates the ability to bind and release vaccine antigens over a range of loads, pH values, and ionic strengths. Poly(lactide-co-glycolide) microparticles were synthesized by a w/o/w emulsification method in the presence of the anionic surfactant DSS (dioctyl sodium sulfosuccinate). Ovalbumin (OVA), carbonic anhydrase (CAN), lysozyme (LYZ), lactic acid dehydrogenase, bovine serum albumin (BSA), an HIV envelope glyocoprotein, and a Neisseria meningitidis B protein were adsorbed to the PLG microparticles, with binding efficiency, initial release and zeta potentials measured. Protein (antigen) binding to PLG microparticles was influenced by both electrostatic interaction and other mechanisms such as van der Waals forces. The protein binding capacity was directly proportional to the available surface area and may have a practical upper limit imposed by the formation of a complete protein monolayer as suggested by AFM images. The protein affinity for the PLG surface depended strongly on the isoelectric point (pI) and electrostatic forces, but also showed contributions from nonCoulombic interactions. Protein antigens were adsorbed on anionic PLG microparticles with varying degrees of efficiency under different conditions such as pH and ionic strength. Observable changes in zeta potentials and morphology suggest the formation of a surface monolayer. Antigen binding and release occur through a combination of electrostatic and van der Waals interactions occurring at the polymer-solution interface.
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PMID:An investigation of the factors controlling the adsorption of protein antigens to anionic PLG microparticles. 1620 Jun 15

N-Heterocyclic cations are incorporated into proteins using 5-(2-bromoethyl)phenanthridinium bromide, which selectively reacts with either cysteine or lysine residues, resulting in ethylphenanthridinium (Phen) or highly stable cyclised dihydro-imidazo-phenanthridinium (DIP) adducts respectively; these modifications have been found to manipulate the observed structure of lysozyme and bovine serum albumin by AFM.
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PMID:Incorporation of N-heterocyclic cations into proteins with a highly directed chemical modification. 1757 44

Inhibiting protein misfolding and aggregation is imperative for treatment of amyloid diseases. In this regard small molecules which bind to and stabilize the monomeric protein have invited attention owing to their ability to significantly slow down or inhibit aggregation and amyloid formation. We have earlier shown that hen egg-white lysozyme (HEWL) spontaneously forms soluble oligomers at pH 12.2, which are later stabilized by intermolecular disulphide bonds, eventually resulting in amyloid fibrils. In this work, we show that overnight ( approximately 12 h) pre-incubation of HEWL with its competitive inhibitor, N,N',N''-Triacetylchitotriose (chitotriose) at neutral pH, impairs its aggregation and fibrillogenesis at pH 12.2. Unlike in control or N-Acetyl-D-glucosamine (NAG) pre-incubated samples, HEWL-chitotriose complex displayed i) reduced thioflavin T and ANS fluorescence, ii) small oligomers but no amyloid fibrils in AFM, iii) absence of large aggregates in SDS-PAGE and gel-filtration elutions, iv) marginally more helical content in CD spectra and v) >70% enzymatic activity after 24 h and approximately 16% activity after week long incubation at alkaline pH. It is likely that strong binding in the HEWL-chitotriose complex, in contrast to weakly bound HEWL-NAG complex, raises the activation energy barrier for protein misfolding and subsequent aggregation, thereby retarding the aggregation kinetics substantially. These results hold promise for the therapy of human lysozyme amyloidosis.
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PMID:Suppression of lysozyme aggregation at alkaline pH by tri-N-acetylchitotriose. 1933 35

The Langmuir-Blodgett (L-B) technique has been employed for the construction of hybrid films consisting of three components: surfactant, clay, and lysozyme (Lys). The surfactants are octadecylammonium chloride (ODAH) and octadecyl ester of rhodamine B (RhB18). The clays include saponite and laponite. Surface pressure versus area isotherms indicate that lysozyme is adsorbed by the surfactant-clay L-B film at the air-water interface without phase transition. The UV-visible spectra of the hybrid film ODAH-saponite-Lys show that the amount of immobilized lysozyme in the hybrid film is (1.3+/-0.2) ng mm(-2). The average surface area (Omega) per molecule of lysozyme is approximately 18.2 nm(2) in the saponite layer. For the multilayer film (ODAH-saponite-Lys)(n), the average amount of lysozyme per layer is (1.0+/-0.1) ng mm(-2). The amount of lysozyme found in the hybrid films of ODAH-laponite-Lys is at the detection limit of about 0.4 ng mm(-2). Attenuated total reflectance (ATR) FTIR spectra give evidence for clay layers, ODAH, lysozyme, and water in the hybrid film. The octadecylammonium cations are partially oxidized to the corresponding carbamate. A weak 1620 cm(-1) band of lysozyme in the hybrid films is reminiscent of the presence of lysozyme aggregates. AFM reveals evidence of randomly oriented saponite layers of various sizes and shapes. Individual lysozyme molecules are not resolved, but aggregates of about 20 nm in diameter are clearly seen. Some aggregates are in contact with the clay mineral layers, others are not. These aggregates are aligned in films deposited at a surface pressure of 20 mN m(-1).
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PMID:Three-component Langmuir-Blodgett films consisting of surfactant, clay mineral, and lysozyme: construction and characterization. 2010 49

As a major constituent of egg white matrix, ovalbumin has long been perceived to be implicated in the formation of avian eggshells, in particular, the mammillary layer. However, very little is known about the detailed mechanism by which this protein mediates shell calcification. By the combined studies of AFM, SEM, and TEM, we have investigated the influence of ovalbumin on CaCO(3) precipitation under in vitro mineralization conditions. We observed that the influence was multifold. This protein modified the morphology of calcite crystals through a distinct anisotropic process with respect to the four crystal step edges. AFM characterization revealed that the modification was initiated at the obtuse-obtuse step corner and propagated predominantly along the obtuse steps. Furthermore, the protein favored the existence of unstable phases such as amorphous calcium carbonate and crystalline vaterite. In contrast, lysozyme, another protein also present in the system, played a very different role in modifying calcite morphology. The mechanistic understanding gained from this study is clearly also of practical significance in developing advanced inorganic CaCO(3) materials with the aid of morphological manipulation of crystalline structures via different protein mediation.
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PMID:Influence of ovalbumin on CaCO3 precipitation during in vitro biomineralization. 2036 64

Silica surfaces were coated with a range of cationic bottle-brush polymers with 45 units long poly(ethylene oxide) side chains, and their efficiency in reducing protein adsorption was probed by QCM-D, reflectometry and AFM. Preadsorbed layers formed by bottle-brush polymers with different side chain to charge ratio was exposed to two proteins with different net charge, lysozyme and BSA. The reduction in protein adsorption was found to depend on both the type of protein and on the nature of the polyelectrolyte layer. The most pronounced reduction in protein adsorption was achieved when the fraction of charged backbone segments was in the range 0.25-0.5 equivalent to a fraction of poly(ethylene oxide) side chains of 0.75-0.5. It was concluded that these polymers have enough electrostatic attachment points to ensure a strong binding to the surface, and at the same time a sufficient amount of poly(ethylene oxide) side chains to counteract protein adsorption. In contrast, a layer formed by a highly charged polyelectrolyte without side chains was unable to resists protein adsorption. On such a layer the adsorption of negatively charged BSA was strongly enhanced, and positively charged lysozyme adsorbed to a similar extent as to bare silica. AFM colloidal probe force measurement between silica surfaces with preadsorbed layers of bottle-brush polymers were conducted before and after exposure to BSA and lysozyme to gain insight into how proteins were incorporated in the bottle-brush polymer layers.
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PMID:Protein interactions with bottle-brush polymer layers: Effect of side chain and charge density ratio probed by QCM-D and AFM. 2057 58


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