Conformational studies of poly(oxyethylene)-bound peptides and protein sequences

Pillai, V. N. Rajasekharan; Mutter, Manfred

doi:10.1021/ar00064a005

Cited by 112 publications

(47 citation statements)

References 59 publications

(24 reference statements)

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“…[35] As a matter of fact, adding a preformed precipitate (composed of G1P material after completion of polycondensation) to initiate a further NCA polycondensation batch did not result in augmented DP n ; the precipitated material was identical to G1P. Upon precipitating, G1P probably aggregates as b sheets (a hypothesis consistent with literature observations on hydrophobic poly(amino acids), [36] and supported by the presence of an absorption band at 1630 cm À1 in the IR spectrum of crude, solid G1P), which is indeed likely to hinder the N termini of peptide chains, [21] thus slowing their reaction with NCA. Such a relationship between peptide insolubility and weak reactivity has also been identified in stepwise peptide synthesis (either by solid or solution-phase methods) with the so-called "difficult sequences".…”

supporting

confidence: 81%

An Expeditious Multigram‐Scale Synthesis of Lysine Dendrigraft (DGL) Polymers by Aqueous N‐Carboxyanhydride Polycondensation

Collet

Souaïd

Cottet

et al. 2010

Chemistry A European J

104

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The synthesis and characterisation of new arborescent architectures of poly(L-lysine), called lysine dendrigraft (DGL) polymers, are described. DGL polymers were prepared through a multiple-generation scheme (up to generation 5) in a weakly acidic aqueous medium by polycondensing N(epsilon)-trifluoroacetyl-L-lysine-N-carboxyanhydride (Lys(Tfa)-NCA) onto the previous generation G(n-1) of DGL, which was used as a macroinitiator. The first generation employed spontaneous NCA polycondensation in water without a macroinitiator; this afforded low-molecular-weight, linear poly(L-lysine) G1 with a polymerisation degree of 8 and a polydispersity index of 1.2. The spontaneous precipitation of the growing N(epsilon)-Tfa-protected polymer (GnP) ensures moderate control of the molecular weight (with unimodal distribution) and easy work-up. The subsequent alkaline removal of Tfa protecting groups afforded generation Gn of DGL as a free form (with 35-60% overall yield from NCA precursor, depending on the DGL generation) that was either used directly in the synthesis of the next generation (G(n+1)) or collected for other uses. Unprotected forms of DGL G1-G5 were characterised by size-exclusion chromatography, capillary electrophoresis and (1)H NMR spectroscopy. The latter technique allowed us to assess the branching density of DGL, the degree of which (ca. 25%) turned out to be intermediate between previously described dendritic graft poly(L-lysines) and lysine dendrimers. An optimised monomer (NCA) versus macroinitiator (DGL G(n-1)) ratio allowed us to obtain unimodal molecular weight distributions with polydispersity indexes ranging from 1.3 to 1.5. Together with the possibility of reaching high molecular weights (with a polymerisation degree of ca. 1000 for G5) within a few synthetic steps, this synthetic route to DGL provides an easy, cost-efficient, multigram-scale access to dendritic polylysines with various potential applications in biology and in other domains.

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supporting

confidence: 81%

An Expeditious Multigram‐Scale Synthesis of Lysine Dendrigraft (DGL) Polymers by Aqueous N‐Carboxyanhydride Polycondensation

Collet

Souaïd

Cottet

et al. 2010

Chemistry A European J

104

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“…Consistent with the pioneering work of Mutter et al on peptide PEGylation, the PEO stabilizes secondary peptide structures and slows down structural transitions (in the case of I and II the statistical segment conformation). [32] No secondary structure transition can be observed for weeks to months (see FigFigure 4. CD spectra showing conjugate II before and after addition of calcium and subsequently of EGTA (a) and non-PEGylated peptide before and after calcium addition (b).…”

Section: +mentioning

confidence: 99%

Calcium Ions to Remotely Control the Reversible Switching of Secondary and Quaternary Structures in Bioconjugates

Kühnle

Börner

2011

Angew Chem Int Ed

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“…Although Deber and co-workers (13,14) have demonstrated that the secondary structural preferences of amino acid residues are context-dependent and that these residues have high helix-forming tendencies in membrane mimetic solvents, this correlation was determined using peptides of a constant length. Studies with short peptides indicate that in solution ␤-sheet formation is maximum for peptides containing 8 -12 residues (15).…”

mentioning

confidence: 99%

The Chain Length Dependence of Helix Formation of the Second Transmembrane Domain of a G Protein-coupled Receptor ofSaccharomyces cerevisiae

Ding¹,

Schreiber²,

VerBerkmoes³

et al. 2002

Journal of Biological Chemistry

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The chain length dependence of helix formation of transmembrane peptides in lipids was investigated using fragments corresponding to the second transmembrane domain of the ␣-factor receptor from Saccharomyces cerevisiae. Seven peptides with chain lengths of 10 (M2-10; FKYLLSNYSS), 14 (M2-14), 18 (M2-18), 22 (M2-22), 26 (M2-26), 30 (M2-30) and 35 (M2-35; RSRKTPIFIINQVSLFLIILH-SALYFKYLLSNYSS) residues, respectively, were synthesized. CD spectra revealed that M2-10 was disor-dered, and all of the other peptides assumed partially ␣-helical secondary structures in 99% trifluoroethanol (TFE)/H 2 O. In 50% TFE/H 2 O, M2-30 assumed a ␤-like structure. The other six peptides exhibited the same CD patterns as those found in 99% TFE/H 2 O. In 1,2-dimyristoyl-snglycero-3-phosphocholine/1,2-dimyristoyl-sn-glycero-3-phospho-rac-(1-glycerol) (4:1 ratio) vesicles, M2-22, M2-26, and M2-35 formed ␣-helical structures, whereas the other peptides formed ␤-like structures. Fourier transform infrared spectroscopy in 1,2-dimyristoyl-sn-glycero-3-phosphocholine/1,2-dimyristoyl-sn-glycero-3-phosphorac-(1-glycerol) (4:1) multilayers showed that M2-10, M2-14, M2-18, and M2-30 assumed ␤-structures in this environment. Another homologous 30-residue pep-tide (M2-30B), missing residues SNYSS from the N terminus and extending to RSRKT on the C terminus, was helical in lipid bilayers, suggesting that residues at the termini of transmembrane domains influence their biophysical properties. Attenuated total reflection Fourier transform infrared spectroscopy revealed that M2-22, M2-26, M2-30B, and M2-35 were ␣-helical and oriented at angles of 12°, 13°, 36°, and 34°, respectively, with respect to the multilayer normal. This study showed that chain length must be taken into consideration when using peptides representing single transmembrane domains as surrogates for regions of an intact receptor. Furthermore, this work indicates that the tilt angle and conformation of transmembrane portions of G protein-coupled receptors may be estimated by detailed spectroscopic measurements of single transmembrane peptides.The folding and structure of integral membrane proteins is driven by entropic factors that cause the apolar side chains of many amino acid residues to seek the interior of lipid bilayers and enthalpic factors that require that the hydrogen bond potential of the peptide group be satisfied in the low dielectric membrane interior (1). Thermodynamic analyses indicate that the ␣-helix is the most favored conformation of membranespanning regions of proteins. Indeed, it is believed that preassembled ␣-helices form in the aqueous cytoplasm of the cell and then insert into the bilayer (2). The thickness of the hydrocarbon milieu of the bilayer depends on the fatty acid composition and is often assumed to be about 30 Å. On this basis, the minimum number of residues that can form an ␣-helix and span the bilayer is predicted to be 20. However, this prediction assumes that the peptide inserts into the membrane parallel to the bilayer normal.Recent x-ray stud...

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Conformational studies of poly(oxyethylene)-bound peptides and protein sequences

Cited by 112 publications

References 59 publications

An Expeditious Multigram‐Scale Synthesis of Lysine Dendrigraft (DGL) Polymers by Aqueous N‐Carboxyanhydride Polycondensation

An Expeditious Multigram‐Scale Synthesis of Lysine Dendrigraft (DGL) Polymers by Aqueous N‐Carboxyanhydride Polycondensation

Calcium Ions to Remotely Control the Reversible Switching of Secondary and Quaternary Structures in Bioconjugates

The Chain Length Dependence of Helix Formation of the Second Transmembrane Domain of a G Protein-coupled Receptor ofSaccharomyces cerevisiae

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