Conformation and orientation of end-grafted (co)polyglutamates and (co)polyaspartates

Oosterling, Michiel L.C.M.; Willems, Edwin; Schouten, A.J.

doi:10.1016/0032-3861(95)96857-5

Cited by 9 publications

(11 citation statements)

References 37 publications

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“…Synthetic poly(γ-alkyl-α- l -glutamates) are polypeptides known to exist in a well-defined α-helical structure and retain this conformation even in solution. − The α-helical structure of many polyglutamates is stabilized by intramolecular hydrogen bonding which gives the polypeptide a rodlike structure. The grafting of such polypeptides to different surfaces has been explored − in association with various applications, including the separation of optical isomers, , and membrane permeability control through the helix-to-coil transition. , Poly(γ-stearyl-α- l -glutamate) (PSLG) is less often studied than poly(γ-benzyl-α- l -glutamate) (PBLG) or poly(ε-carbobenzoxy- l -lysine) (PCBL); unlike these mainstays, it has the desirable feature of being soluble in nonpolar organic solvents. PSLG features an α-helical backbone surrounded by long, flexible side chains and is often called a hairy rodlike polymer. ,− The stearyl chains impart good solubility to this polypeptide, which shows both lyotropic and thermotropic properties. − PSLG-grafted membranes have been shown to increase the activity retention and thermal stability of lipases immobilized on them, which is due to the enhanced hydrophobic interaction between the lipase and the long stearyl chains. , Sackmann suggested that hairy rod polymers such as PSLG can be deposited on substrates, which can be further used to support biomimetic membranes by a self-assembly process .…”

Section: Introductionmentioning

confidence: 99%

“…[8][9][10][11] The R-helical structure of many polyglutamates is stabilized by intramolecular hydrogen bonding which gives the polypeptide a rodlike structure. The grafting of such polypeptides to different surfaces has been explored [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] in association with various applications, including the separation of optical isomers, 19,27 and membrane permeability control through the helix-to-coil transition. 26,27 Poly(γ-stearyl-R-L-glutamate) (PSLG) is less often studied than poly(γbenzyl-R-L-glutamate) (PBLG) or poly(ε-carbobenzoxy-L-lysine) (PCBL); unlike these mainstays, it has the desirable feature of being soluble in nonpolar organic solvents.…”

Section: Introductionmentioning

confidence: 99%

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Preparation of Organosoluble Silica−Polypeptide Particles by “Click” Chemistry

et al. 2009

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The synthesis of organo-soluble hybrid particles with a hydrophobic, R-helical polypeptide shell and silica core has been achieved by combining ring-opening polymerization and click chemistry. Alkyne end-terminated poly(γ-stearyl-R-L-glutamate) (alkyne-PSLG) was prepared by the ring-opening polymerization of the N-carboxyanhydride of γ-stearyl-R-L-glutamate using propargylamine as initiator. The molecular weight and structure of this polypeptide were characterized by GPC and MALDI, and the R-helical nature was established by 1 H NMR and FTIR. Azide-functionalized silica particles (azido-silica) were prepared by the functionalization of silica particles with 3-bromopropyltrichlorosilane followed by nucleophilic substitution with sodium azide. The azide functionalization was confirmed by FTIR and XPS. Alkyne-PSLG was coupled to azido-silica by click reaction in tetrahydrofuran or toluene in the presence of pentamethyldiethylenetriamine and copper(I) bromide. Further characterization of the product using XPS, FTIR, and 1 H NMR revealed that the grafted polypeptide retained its R-helical nature and formed colloidal particles that readily dispersed in organic solvents. These hydrophobic, polypeptide-functionalized particles can serve as model systems in studies of colloid dynamics and/or crystallization. They may also find use in investigations designed to model enzyme activation or the properties of hydrophobic proteins in cell membranes.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Preparation of Organosoluble Silica−Polypeptide Particles by “Click” Chemistry

et al. 2009

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“…To overcome these disadvantages some authors tried the so-called ”grafting-from” method. ,− This method uses relatively small monomers, which can easily reach the initiator sites on the substrate. So, these polymers actually grow from the substrates.…”

Section: Introductionmentioning

confidence: 99%

Surface Grafting of Poly(l-glutamates). 1. Synthesis and Characterization

et al. 2001

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The ring-opening polymerization of N-carboxyanhydrides (NCA) of γ-benzyl L-glutamate and γ-methyl L-glutamate from (γ-aminopropyl)triethoxysilane (APS) pretreated substrates such as silicon wafers and quartz slides was investigated. FT-IR transmission spectroscopy, circular dichroism measurements, and UV/vis spectroscopy confirmed the pure R-helix conformation of the grafted polypeptide layers. FT-IR spectroscopy also showed that the most important part of the polymer growth took place in the first 5 h of the polymerization. The average orientation of the rather rigid R-helical polypeptides, grown during a short period of time, was more perpendicular with respect to the substrate than the orientation of the polymers grown over a longer reaction time. For concentrations up to 2.0 M, the polymer growth from both NCA monomers showed a pronounced dependence on the monomer concentration. Moreover, it appeared that the higher the monomer concentration, the more perpendicular the average orientation of the helices with respect to the substrate. The thickness of the grafted polypeptide layers up to 400 Å was determined with ellipsometry and small-angle X-ray reflection measurements. The absence of chemical chain termination was demonstrated by additional polymer growth in a renewed polymerization.

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“…In the “grafting-from” method, − immobilized initiators on substrates are brought in contact with dissolved monomers to obtain covalently bonded polymer chains on the substrate. Primary amines can be used as initiators for the ring-opening polymerization of N -carboxyanhydrides of various amino acid esters.…”

Section: Introductionmentioning

confidence: 99%

Surface Grafting of Poly(l-glutamates). 3. Block Copolymerization

et al. 2001

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This paper describes for the first time the synthesis of surface-grafted AB-block copolypeptides, consisting of poly(γ-benzyl L-glutamate) (PBLG) as the A-block and poly(γ-methyl L-glutamate) (PMLG) as the B-block. Immobilized primary amine groups of (γ-aminopropyl)triethoxysilane (APS) on silicon wafers initiated the ring-opening polymerization of N-carboxyanhydrides of glutamic acid esters (NCAs). After removal of the BLG-NCA monomer solution after a certain reaction time, the amine end groups of the formed PBLG blocks acted as initiators for the second monomers. This method provides the possibility of making layered structures of surface-grafted block copolymers with tuned properties. Ellipsometry and small-angle X-ray reflection (SAXR) measurements revealed the thickness of the polypeptide layers ranging from 45-100 Å of the first block to 140-270 Å for the total block copolypeptides. The chemical composition of the blocks was determined by X-ray photoelectron spectroscopy (XPS). In addition, Fourier transform infrared transmission spectroscopy (FT-IR) revealed that the polypeptide main chains of both blocks consisted of pure R-helices. The average orientation of the helices ranging from 22-42°with respect to the substrate within the first block to 31-35°in the second block could be derived with FT-IR as well.

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Conformation and orientation of end-grafted (co)polyglutamates and (co)polyaspartates

Cited by 9 publications

References 37 publications

Preparation of Organosoluble Silica−Polypeptide Particles by “Click” Chemistry

Preparation of Organosoluble Silica−Polypeptide Particles by “Click” Chemistry

Surface Grafting of Poly(l-glutamates). 1. Synthesis and Characterization

Surface Grafting of Poly(l-glutamates). 3. Block Copolymerization

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