Coherence transfer by isotropic mixing: Application to proton correlation spectroscopy

Braunschweiler, L; Ernst, R. R.

doi:10.1016/0022-2364(83)90226-3

Cited by 2,180 publications

(1,782 citation statements)

References 14 publications

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“…1 H one-dimensional and two-dimensional 1 H total correlation spectroscopy [TOCSY (30)] spectra were collected for the Ace-(Pro)7-Gly-Tyr-NH2 peptide (PPP), along with a 1 H one-dimensional spectrum for monomeric proline. Samples were dissolved in 10% D 2 O/ FIGURE 1: Host-peptide design and cartoon of an ideal PPII helix formed by poly(proline).…”

Section: Host-guest Experimentsmentioning

confidence: 99%

Host−Guest Study of Left-Handed Polyproline II Helix Formation

et al. 2001

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The importance of the left-handed polyproline II (PPII) helical conformation has recently become apparent. This conformation generally is involved in two important functions: protein-protein interactions and structural integrity. PPII helices play vital roles in a variety of processes including signal transduction, transcription, and cell motility. Proline-rich regions of sequence are often assumed to adopt this structure. Remarkably, little is known about the physical determinants of this secondary structure type. In this study, we have explored the formation of PPII helices by a short poly(proline) peptide. In addition, the results from experiments used to determine the propensities for apolar residues, plus glycine, asparagine, and glutamine, to adopt this structure in a poly(proline)-based host peptide are reported here. Proline possesses the highest intrinsic propensity, with glutamine, alanine, and glycine having surprisingly high propensities.-Branched residues possess the lowest propensities of the residues examined. It is postulated that propensities possessed by apolar residues are due in part to peptide-solvent interactions, and that the remarkably high propensity possessed by glutamine may be due to a side chain to backbone hydrogen bond. These data are the first step toward a molecular understanding of the formation of this important, and yet little studied, secondary structure.In recent years, the left-handed polyproline II (PPII) 1 helical conformation has been elevated from the status of a relatively rare and seemingly uninteresting secondary structure to one that is surprisingly common and of the utmost importance. This structure plays a central role in numerous vital processes including signal transduction, transcription, cell motility, and the immune response. Proline-rich ligands of the cytoskeletal protein profilin (1), as well as those of the SH3, WW, and EVH1 protein interaction domains, are bound in this conformation (2). The peptide ligands of class II MHC molecules are also bound in the PPII conformation (3). PPII helices are major features of collagens (4) and plant cell wall proteins (5). The PPII helix is believed to be the dominant conformation for many proline-rich regions of sequence (PRRs) (6). Sequences not rich in proline also adopt this structure. For example, poly(lysine), poly(glutamate), and poly(aspartate) peptides form PPII helices (7). Around 2% of all residues in known protein structures are found in PPII helices at least four residues long (8, 9). As many as 10% of all residues are found in the PPII conformation, although not necessarily as part of PPII helices (10). PPII helices have also been hypothesized to be a major component of protein denatured states (11-14), giving them a role in a most fundamental process. Recently, Blanch et al. (15) have suggested that the PPII helix might be the precursor conformation in amyloid formation. Given the preceding, it is truly remarkable how little is known about the physical determinants of the PPII helical conformat...

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Section: Host-guest Experimentsmentioning

confidence: 99%

Host−Guest Study of Left-Handed Polyproline II Helix Formation

et al. 2001

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“…90% H20/10% DzO, 0.10 M deuterated DTT (pH 5.0). The TOCSY experiments (Braunshweiler & Ernst, 1983) were carried out using 35-125 ms mixing time. The mixing time in the NOESY experiments (Kumar et al,198 1) varied between 100 and 300 ms. All experiments were performed with a sweep width of 6,000 Hz, at room temperature (approximately 20 "C) unless specified otherwise.…”

Section: Reduction and Carbo~yme~h~la~~on Of Cysteine Residuesmentioning

confidence: 99%

Bacterial expression and characterization of the CREB bZip module: Circular dichroism and 2D ¹H‐NMR studies

et al. 1993

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In this paper we describe the expression and purification from bacteria of the recombinant basic leucine zipper (bZip) domain of the cAMP response element binding protein, CREB327. The bZip peptide, CREB259–327, purified to near homogeneity, maintains the sequence‐specific CRE site recognition demonstrated by in vitro competition assays. Alkylation of the three cysteine residues of CREB259–327 was employed to prevent aggregation of the peptide due to cysteine oxidation. The Kd of the purified native and modified CREB259–327 for the CRE site was determined by gel retardation assays to be on the order of 10−7 M. We employed CD spectroscopy to study the folding properties of the native and modified CREB259–327. The CD analyses of the native/modified CREB259–327 peptide demonstrated a 20% increase in the α‐helical content upon binding to the cAMP response‐element. Only a 5% increase in the α‐helical content of CREB259–327 is observed upon binding to the AP‐1 site. This observation contrasts with CREB from the GCN4 protein (Weiss, M.A., et al., 1990, Nature 347, 575–578). In addition, the two‐dimensional (2D) 1H‐NMR studies of the bZip CREB peptide further support the distinct features of the CREB protein, in comparison to GCN4. Analysis by CD and 2D NMR of the dimerization domain of CREB suggests that the distinct DNA binding characteristics of CREB reside in the basic portion of the bZip module.

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“…Hence in this analogy the well known conservation of the total polarization P = P 1 + P 2 + P 3 under isotropic mixing conditions (4,5) corresponds to the conservation of the total energy in the pendulum system. It is interesting to note that in the quantum system the conservation of the norm of the density operator under unitary evolution (3) results in the conservation of the term…”

Section: Discussionmentioning

confidence: 95%

“…Under the action of an isotropic mixing Hamiltonian, the initial polarization of a given spin is transferred throughout a coupling network in a coherent way (4,5). For an initial spin density operator…”

Section: Theorymentioning

confidence: 99%

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Spins swing like pendulums do: an exact classical model for TOCSY transfer in systems of three isotropically coupled spins 1/2

Marx

Glaser

2003

Journal of Magnetic Resonance

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Coherence transfer by isotropic mixing: Application to proton correlation spectroscopy

Cited by 2,180 publications

References 14 publications

Host−Guest Study of Left-Handed Polyproline II Helix Formation

Host−Guest Study of Left-Handed Polyproline II Helix Formation

Bacterial expression and characterization of the CREB bZip module: Circular dichroism and 2D ¹H‐NMR studies

Spins swing like pendulums do: an exact classical model for TOCSY transfer in systems of three isotropically coupled spins 1/2

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Coherence transfer by isotropic mixing: Application to proton correlation spectroscopy

Cited by 2,180 publications

References 14 publications

Host−Guest Study of Left-Handed Polyproline II Helix Formation

Host−Guest Study of Left-Handed Polyproline II Helix Formation

Bacterial expression and characterization of the CREB bZip module: Circular dichroism and 2D 1H‐NMR studies

Spins swing like pendulums do: an exact classical model for TOCSY transfer in systems of three isotropically coupled spins 1/2

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Bacterial expression and characterization of the CREB bZip module: Circular dichroism and 2D ¹H‐NMR studies