Poly Γ-methyl L-glutamate Research Articles

Patterning of Polypeptide Thin Films by the Combination of Surface‐Initiated Vapor‐Deposition Polymerization and Photolithography

A solvent‐free strategy offering a fast, economical, and clean approach to integrate polypeptide materials into micrometer‐scale devices is presented. The dimensions and compositions can be controlled in both the lateral and vertical directions. The Figure shows a surface‐grafted pattern composed of PMLG (poly(γ‐methyl‐L‐glutamate)) and PMLG‐b‐PBLG, (B indicates benzyl instead of methyl).

The temperature dependence of mixed monolayers of poly-γ-methyl- l-glutamate and palmitic acid at the air/water interface

There is a flat region (plateau region) ascribed to the transition from monolayer to bilayer in the surface pressure ( F)-area ( A) isotherm of poly-γ-methyl- l-glutamate (PMLG) at the air/water interface. The change in entropy from initial to final state of this transition is very small and negative. This indicates that the order in the monolayer and bilayer states is almost the same but that the former is a little more random. At or below 20°C, the monolayer of palmitic acid (PA) forms a solid condensed film and no difference in the F- A isotherm was detected regardless of temperature. However, there is a break at about 16.8°C in the curve of temperature versus surface pressure of the flat region in the F- A isotherm corresponding to the collapse of the PA monolayer. This suggests that the monolayer states of PA above and below 16.8°C are different. PA at or above 20°C is more miscible with PMLG in the monolayer state than PA at or below 15°C. The difference between miscibility of PMLG in the monolayer state and PA at or above 20°C and at or below 15°C can perhaps be ascribed to the difference between the monolayer states of PA above and below ca. 16.8°C.

The interaction between synthetic polypeptides and fatty acids at the air/water interface

The interactions between synthetic polypeptides having α-helical conformation and fatty acids in monolayer on a pure water surface were studied by surface pressure measurement. Poly-γ-benzyl- l-glutamate (PBLG) and poly-γ-methyl- l-glutamate (PMLG) were used as the synthetic polypeptides, and stearic and palmitic acid as the fatty acids. At a molar ratio of PBLG to stearic or palmitic acid of more than 10 to 1, the fatty acid molecules seem to be intercalated into the side chains of PBLG. At a lower ratio, the miscibility of PBLG in the monolayer state with the fatty acid depends on whether the monolayer of fatty acid shows the liquid condensed film. PBLG in multilayer state is not miscible with the two fatty acids. The miscibility of PMLG in the monolayer state with stearic or palmitic acid also depends on the monolayer state of the fatty acid. PMLG in the multilayer state is miscible with the two fatty acids. PBLG shows better miscibility with the two fatty acids than PMLG. Palmitic acid shows better miscibility with the two peptides than stearic acid.

Substituted polymethylglutamate membrane for immobilization of urease

Poly-γ-methyl- l-glutamate (PMG) was modified and used for enzyme immobilization. Trichloroethyl ester (TCE) and three kinds of amino groups (ethylenediamine, ED; 1,8-diamino-4-amino-methyloctane, TA; polyethyleneimine, PEI) were introduced into the pendant group of PMG. A membrane was prepared from these polymers for enzyme immobilization. Urease was immobilized on each membrane using glutaraldehyde or water-soluble carbodiimide. Urease was very stable when it was immobilized with water-soluble carbodiimide on the membrane having PEI in the pendant group. The characteristics of immobilized urease were also discussed.

Micro Ammonia Sensor

Abstract A micro ammonia sensor, consisting of an ISFET covered with a dry membrane which is made from nonactin and substituted poly-γ-methyl-L-glutamate (PMG) is described. The gate output voltage of the micro ammonia sensor increased with NH4OH addition. The response time of the sensor was 2 min at 30°C, and the sensor exhibited superior selectivity for NH4 + compared to a pH sensitive ISFET.

Pure and mixed monolayers of poly-L-methionine and poly-?y-methyl-L-glutamate with 1,2 dioleyl-L-?-phosphatidylcholine at air-water interface

Monolayers of poly-L-methionine (PM) and poly-γ-methyl-L-glutamate (PMG), spread at an air-water interface, exhibit a high compressibility plateau region at 10 dyn/cm and 18 dyn/cm in their respectiveπ-A curves. This behaviour is related to aα-helical conformation of the polypeptide molecules in the said interface.

Shear piezoelectricity in ethylene dichloride solution of poly-γ-methyl-L-glutamate

When ultrasonic shearing stress is applied to electrically oriented α-helical molecules of poly-γ-methyl-L-glutamate (PMG) in solution, electric potential is observed in the direction perpendicular to the plane of the shear stress. The apparent shear pizeoelectric coefficient is about 1×10−9 V m2/N and five orders of magnitude as small as that for the oriented solid PMG. The effect is not observed for PMG solutions with non-α-helical solvents such as dichloroacetic acid, which suggest that the effect is due to shear piezoelectricity in α-helical polypeptides.

Studies of poly-γ-methyl- l-glutamate monolayers by infrared ATR and transmission spectroscopy and electron microscopy

Polarized infrared ATR and transmission spectra were studied of built-up films of poly-γ-methyl- l-glutamate (PMLG) transferred onto a germanium plate at 15 and 22 mN·m −1, which are below and above an apparent plateau region, respectively, in the surface pressure (π)-area ( A) isotherm. Electron photomicrographs of these films were also obtained by using the folding method, and the film thickness was measured. It was concluded from results of these experiments that the PMLG molecules were in the α-helical conformation and helix axes lay flat on the water surface as condensed ordered arrays forming a certain angle with the compressing direction. The plateau region in the π- A isotherm was ascribed to a transition process from monolayer to bilayer, the molecular conformation as well as orientation being left unchanged.

Circular dichroism of polypeptide monolayers

The circular dichroism (CD) spectra of Langmuir—Blodgett monolayers and collapsed films of poly-γ-methyl- l-glutamate (PMG) and poly- l-alanine (PA) collected from the air-water interface of a Langmuir film balance have been determined. The polypeptide films were formed by spreading from a variety of solvents, followed by transfer to quartz plates for CD spectrophotometry. When all plates were aligned identically in the light beam of the spectropolarimeter, films of PMG and PA exhibited linear dichroism which could be used to determine the orientation of the polymer chains on the surface of the film balance. True CD spectra, free of linear component, were obtained on films oriented at numerous angles around the axis of the incident light beam. The CD spectra of films of PA and PMG in the α-helical conformation were consistent with the optical properties expected of polypeptides which have the helix axis perpendicular to the direction of propagation of light. PMG films gave spectra characteristic of the α-helix or β-conformation, depending on the spreading solvent used to form the monolayers. The pressure-area and surface potential curves, as well as the interpretation of the CD spectra of PMG and PA films, were all consistent with the results of previous investigations employing infrared spectroscopy. Details of preparing and mounting polypeptide monolayers for CD spectroscopy are given.

Anisotropy study of electrical conduction in oriented polymers. II. Anisotropy of electrical conduction in uniaxially oriented polymers

Conductivity σ (γ) in uniaxially oriented polymers is presented as a function of the angle γ between the orientation axis and electric field, resulting in the form σ (γ) ∝1+h cos2γ, where h is given as a function of both orientation and conductivity of the polymer crystallite. The anisotropy of conductivity is obtained in uniaxially oriented samples of poly-γ-methyl-L-glutamate (PMG) and of Nylon 12 (N12). Conductivity is largest parallel to the orientation axis in PMG and is largest perpendicular to the orientation axis in N12. These correspond to the direction of the hydrogen bonding orientation. This is very obvious evidence that charge carriers flow along a direction parallel to hydrogen bonding. Anisotropy of conductivity in crystallite is estimated using an orientation parameter and anisotropy of the observed conductivity.

Interfacial conformational modifications in a polypeptide

Poly-γ-methyl- l-glutamate (PMG) spread as a monolayer at the air/water interface is capable of existing either in the α (helix coil) or in the β (pleated sheet) conformations. By suitable choice of a spreading solvent, the investigator may control which conformation is dominantly present in the interface. The β conformer is characterized by a high surface viscosity which fails with rising temperature, while the a conformer at an equivalent surface concentration exhibits a relatively low surface viscosity which increases irreversibly with temperature. We interpret these results to mean that the a helices are partly denatured by the surface environment, while the intermolecular hydrogen bonds in the β structure are weakened by rising temperature. In no case examined by us in a complete denaturation of the a helices to the β structure observed.

Relaxation phenomena of poly-γ-benzyl-L-glutamate, poly-γ-methyl-L-glutamate, and copoly(γ-methyl-L-glutamate, γ-benzyl-L-glutamate)

Abstract Relaxation phenomena of poly-α-amino acids in the solid state have been investigated using poly-γ-benzyl-L-glutamate (PBLG), poly-γ-methyl-L-glutamate (PMLG), and copoly (γ-methyl-L-glutamate, γ-benzyl-L-glutamate) (PMBG) by means of dielectric, dynamic mechanical, NMR, dilatometric, and X-ray diffraction measurements at temperatures between −196 and 180°C. Each of the samples exhibits two relaxation regions, one at room temperature (β-relaxation) and the other in the range from −150 to −100°C (γ-relaxation). The γ-relaxation is attributed to motion of the side chains with small amplitude. The β-relaxation is due to large-scale motion of the side chain. It has been found that the β-relaxation is well described by the WLF-equation. The intensity of the X-ray diffraction peak at 2θ = 7° for PBLG increases with increasing temperature, which is similar to results obtained in small-angle X-ray scattering for polymer crystals consisting of two phases, amorphous and crystalline. A break point is observe...

TREATMENTS OF POLY-γ-METHYL-L-GLUTAMATE FIBERS WITH SULFURIC ACID

Undrawn and drawn poly-γ-methyl-L-glutamate (PMLG) fibers having different secondary structures were treated with 18N sulfuric acid, and the apparent weight loss was measured. From quantitative analysis by infrared spectra of the hydrolysis degree of side chain ester groups in insoluble residue, the apparent weight loss was devided into the weight loss due to hydrolysis of main chain and that of side chain. Besides, the density and intrinsic viscosity of insoluble residue were measured, and the accessibility of PMLG fibers to sulfuric acid is discussed in connection with secondary structures. The results were as follows;(1) In both PMLG fibers, the weight loss due to hydrolysis of main chain proceeds at two stages, the early stage of higher rate and the later one of lower and constant rate. The former is considered to be due to the dissolution of more accessible amorphous region from the decreasing behavior of intrinsic viscosity of insoluble residue. The weight loss due to hydrolysis of main chain in the first stage is larger in undrawn fiber and therefore it is considered that undrawn fiber has larger accessibility than drawn fiber.(2) Density of insoluble residue supports quantitative analysis of the hydrolysis degree of side chain by infrared spectra.(3) The difference of accessibility to sulfuric acid between undrawn and drawn fibers was concluded to be caused by the following facts. Since random-coil structure is difficult to be recognized in both fibers, the region where α-helix dose not stand side by side but stand random situation in undrawn fiber decrease during the α→β transformation by drawing.