[4] Circular dichroism

Woody, Robert W.

doi:10.1016/0076-6879(95)46006-3

Cited by 818 publications

(627 citation statements)

References 153 publications

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“…In buffer solution the spectra of both samples are similar with the exception of an additional ellipticity at 232 nm in the glycosylated analogue. This region of the spectrum indicates the presence of a bend or turn-type motif [31]. As the lipophilic character of the solvent is increased, this shoulder is consistently larger in the glycosylated analogue.…”

Section: Resultsmentioning

confidence: 91%

Structural comparison of a 15 residue peptide from the V3 loop of HIV‐1_IIIb and an O‐glycosylated analogue

et al. 1996

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As part of a program to study the effect of glycosylation on the three-dimensional structures of HIV-ImB V3 peptide constructs, we have examined the solution structures of a 15 residue peptide (RIQRGPGRAFVTIGK, P18ms), originally mapped as an epitope recognized by CD8 + D u class I MHC-restricted murine cytotoxic T-lymphocytes (CTL), and an analogue (P18mB-g), O-glycosylated with an t~-galactosamine on Thr-12, using NMR, circular dichroism and molecular modeling methods. Our studies show that the peptides sample mainly random conformations in aqueous solution near 25°C and become more ordered by the addition of trifluoroethanol. Upon decreasing the temperature to 5°C, a reverse turn is formed around the immunodominant tip (GS-RS). Glycosylation on T Iz 'tightens' the turn slightly as suggested by NOE and CD analysis. In addition, the sugar has a defined conformation with respect to the peptide backbone and influences the local peptide conformation. These data suggest that simple glycosylation may influence the conformational equilibrium of a V3 peptide which contains a domain critical for antibody recognition and virus neutralization. We also show that the ability of cytotoxic Tlymphocytes (CTL) to lyse tumor cells presenting P18ttm was completely abrogated by threonine glycosylation.

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Section: Resultsmentioning

confidence: 91%

Structural comparison of a 15 residue peptide from the V3 loop of HIV‐1_IIIb and an O‐glycosylated analogue

et al. 1996

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“…The positive band at 228 nm was not present in the spectrum of the oC trimer; instead, a double minimum at 208 and 222 nm and a maximum at 190 nm were observed. These bands are indicative of ␣-helix (50). When the contribution of C is subtracted from the observed oC spectrum, the resulting spectrum resembles that expected for a coiled-coil (Fig.…”

Section: Table IIImentioning

confidence: 92%

Physical Characterization of the Procollagen Module of Human Thrombospondin 1 Expressed in Insect Cells

Misenheimer

Huwiler

Annis

et al. 2000

Journal of Biological Chemistry

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Thrombospondin 1 (TSP1) is a homotrimeric glycoprotein composed of 150-kDa subunits connected by disulfide bridges. The procollagen module of thrombospondin 1 has been implicated in antiangiogenic activity. Procollagen modules are found in a number of extracellular proteins and are identifiable by 10 cysteines with characteristic spacing. We expressed and studied the procollagen module (C) of human TSP1, both by itself and in the context of the adjoining oligomerization sequence (o) and N-terminal module (N). The coding sequences were introduced into baculoviruses along with an N-terminal signal sequence and C-terminal polyhistidine tag. Proteins were purified from conditioned medium of infected insect cells by nickel-chelate chromatography. NoC is a disulfide bonded trimer and cleaves readily at a site of preferential proteolysis to yield monomeric N and trimeric oC. These are known properties of full-length TSP1. Mass spectroscopy indicated that C is N-glycosylated, and all 10 cysteine residues of C are in disulfides. By equilibrium ultracentrifugation, C is a monomer in physiological salt solution. Circular dichroism, intrinsic fluorescence, and differential scanning calorimetry experiments suggest that the stability of C is determined by the disulfides. The two tryptophans of C are in a polar, exposed environment as assessed by iodide fluorescence quenching and solvent perturbation. The oC far UV circular dichroism spectrum could be modeled as the sum of C and a coiled-coil oligomerization domain. The results indicate that the recombinant C folds autonomously into its native structure, and trimerization of the modules in TSP1 does not perturb their structures.

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“…An increase in the intensity of the 240-nm band, a decrease as well as a red shift of the 265-nm band, and a red shift of the crossover from 239 nm to 241 nm indicate a marginal distortion of the A-form helix towards the B-form [13]. Between 240 and 300 nm no contribution of the peptide CD spectrum is expected, ensuring that the observed changes originate exclusively from the RNA [28]. TAR was previously suggested to adopt B-helix character on binding of smaller Tat-related peptides [13], in agreement with FTIR results.…”

Section: Spectroscopymentioning

confidence: 96%

“…5) should provide a rough guess of the CD spectrum of the bound peptide, and previous studies show that difference-CD spectra are well suited to predict the secondary structures correctly [15,16,29]. According to this procedure, the minimum of molar ellipticity is shifted to 217 nm, an effect typical of polypeptides adopting extended conformations, such as 13-strands [28]. As TAR may also contribute to this far-UV region, the extended conformation of bound BP1 cannot be determined safely from this approach.…”

Section: Spectroscopymentioning

confidence: 99%

Structural rearrangements on HIV‐1 Tat (32–72) TAR complex formation

et al. 1996

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[4] Circular dichroism

Cited by 818 publications

References 153 publications

Structural comparison of a 15 residue peptide from the V3 loop of HIV‐1_IIIb and an O‐glycosylated analogue

Structural comparison of a 15 residue peptide from the V3 loop of HIV‐1_IIIb and an O‐glycosylated analogue

Physical Characterization of the Procollagen Module of Human Thrombospondin 1 Expressed in Insect Cells

Structural rearrangements on HIV‐1 Tat (32–72) TAR complex formation

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[4] Circular dichroism

Cited by 818 publications

References 153 publications

Structural comparison of a 15 residue peptide from the V3 loop of HIV‐1IIIb and an O‐glycosylated analogue

Structural comparison of a 15 residue peptide from the V3 loop of HIV‐1IIIb and an O‐glycosylated analogue

Physical Characterization of the Procollagen Module of Human Thrombospondin 1 Expressed in Insect Cells

Structural rearrangements on HIV‐1 Tat (32–72) TAR complex formation

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Structural comparison of a 15 residue peptide from the V3 loop of HIV‐1_IIIb and an O‐glycosylated analogue

Structural comparison of a 15 residue peptide from the V3 loop of HIV‐1_IIIb and an O‐glycosylated analogue