A New Mechanism for Metal Ion-assisted Interchain Helix Assembly in a Naturally Occurring Peptide Mediated by Optimally Spaced γ-Carboxyglutamic Acid Residues

Dai, Qiuyun; Prorok, Mary

doi:10.1016/j.jmb.2003.12.027

Cited by 33 publications

(61 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…All Fmoc-derivatized amino acids were obtained from either Sigma or Novabiochem (San Diego, CA) with the exception of Fmoc-␥,␥Ј-di-o-tBu-L-Gla, which was synthesized as reported earlier (14). The purification of nonCys and Cys-containing peptides has been described previously, as has the oxidation of the Cys-containing variants to provide the disulfide-linked species (10). All peptides were characterized by analytical HPLC and delayed extraction matrix-assisted laser desorption ionization-time-of-flight mass spectrometry on a Voyager-DE spectrometer (PerSeptive Biosystems, Framingham, MA).…”

Section: Methodsmentioning

confidence: 99%

“…Sedimentation Equilibrium Ultracentrifugation-Sedimentation equilibrium experiments were performed on an Optima XL-I analytical ultracentrifuge in an An-60 Ti rotor equipped with a standard two-channel cell (10). The initial peptide concentration for all runs was 150 M. The buffer consisted of 10 mM sodium borate, 100 mM NaCl, pH 6.5.…”

Section: Methodsmentioning

confidence: 99%

“…The partial specific volume of Gla was assigned that of Glu. The fractional dimer content (f di ) was calculated using the equation, f di ϭ (M r(app) Ϫ M r(mono) Ϫ nM r(metal) )/M r(mono) ϩ nM r(metal) (10). The stoichiometries (n) of Ca 2ϩ binding to peptides 1, 5, 6, 8, 9, and 10 were determined from titration calorimetry (17).…”

Section: Methodsmentioning

confidence: 99%

“…Section 1734 solely to indicate this fact. 1 allow for the adoption of helical dimers in the presence of Ca 2ϩ (10). This conclusion, based on sedimentation equilibrium studies with con-G and con-G derivatives, and thiol-disulfide rearrangement assays with Cys-containing versions of con-G, suggested a model for the dimer in which helix-helix interactions are primarily maintained through interhelical Gla-Ca 2ϩ coordination between peptide strands aligned in antiparallel fashion.…”

mentioning

confidence: 94%

See 3 more Smart Citations

Helix-Helix Interactions between Homo- and Heterodimeric γ-Carboxyglutamate-containing Conantokin Peptides and Their Derivatives

Dai

Sheng

Geiger

et al. 2007

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

The conantokins are a family of small, naturally occurring ␥-carboxyglutamate (Gla)-rich peptides that specifically antagonize the N-methyl-D-aspartate (NMDA) subtype of ionotropic glutamate receptor. One member of this family, conantokin-G (con-G), undergoes Ca 2؉ -mediated self-assembly to form an antiparallel helical dimer. Subunit interactions in this complex are incumbent upon intermolecular Ca 2؉ bridging of Gla residues spaced at i, i ؉ 4, i ؉ 7, i ؉ 11 intervals within the monomer. Herein, we further probe the molecular determinants governing such helix-helix interactions. Select variants were synthesized to evaluate the contributions of non-Gla residues to conantokin self-association. Con-G dimerization was shown to be exothermic and accompanied by positive heat capacity changes. Using positional Gla variants of conantokin-R (con-R), a non-dimerizing conantokin, i, i ؉ 4, i ؉ 7, i ؉ 11 Gla spacing alone was shown to be insufficient for self-assembly. The Ca 2؉ -dependent antiparallel heterodimerization of con-G and con-T(K7␥), two peptides that harbor optimal Gla spacing, was established. Last, the effects of covalently constrained con-G dipeptides on NMDA-evoked current in HEK293 cells expressing combinations of NR1a, NR1b, NR2A, and NR2B subunits of the NMDA receptor were investigated. The antiparallel dipeptide was unique in its ability to potentiate current at NR1a/2A receptors and, like monomeric con-G, was inhibitory at NR1a/2B and NR1b/2B combinations. In contrast, the parallel species was completely inactive at all subunit combinations tested. These results suggest that, under physiological Ca 2؉ concentrations, equilibrium levels of con-G dimer most likely exist in an antiparallel orientation and exert effects on NMDA receptor activity that differ from the monomer.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 94%

See 2 more Smart Citations

Helix-Helix Interactions between Homo- and Heterodimeric γ-Carboxyglutamate-containing Conantokin Peptides and Their Derivatives

Dai

Sheng

Geiger

et al. 2007

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…Of the conantokins discovered and characterized thus far, up to five Gla residues have been observed in a single conantokin, distributed at i,iϩ4, i,iϩ7, and/or i,iϩ11 intervals along the primary sequence. When Ca 2ϩ is present, Gla residues act as a "zipper" by coordinating Ca 2ϩ , stabilizing the ␣-helical conformation (3,4).…”

mentioning

confidence: 99%

Stapling Mimics Noncovalent Interactions of γ-Carboxyglutamates in Conantokins, Peptidic Antagonists of N-Methyl-d-Aspartic Acid Receptors

Platt

Han

Green

et al. 2012

Journal of Biological Chemistry

View full text Add to dashboard Cite

Background: Can dicarba bridges (stapling) replace noncovalent interactions that stabilize helical conformation of neuroactive peptides? Results: A rational design, synthesis, structural, and functional characterization of stapled conG analogs that target NMDA receptors is reported. Conclusion: Stapled conG analogs are potent antagonists of NMDA receptors and anticonvulsant compounds. Significance: Stapling can be successfully applied to convert neuroactive peptides into drug leads.

show abstract

Circular Dichroism ( CD ) Spectroscopy

Presta¹,

Stillman²

2005

Encyclopedia of Inorganic Chemistry

View full text Add to dashboard Cite

Circular dichroism (CD) spectroscopy is of fundamental importance as a tool in all areas of chemistry and biochemistry because this technique is the simplest and fastest measure of the presence of the chiral species that lead to optical activity. Chiral centers and chiral species exist from the simplest molecules to complex organic molecules, from inorganic complexes to metal‐based biological molecules, typically metalloproteins; from folded polymers, which are typically peptides and proteins; to the supramolecular organization of the quaternary structure of proteins; including all forms of helical structure typified by the the double helix; to liquid crystals and beyond, to even more massive and organized species. For all these species, CD spectroscopy provides insight into the presence and the extent of the chiral electric field induced by the atomic and molecular organization. The optical activity is detected under electronic and vibrational absorption bands as a result of the differential absorption of left‐ and right‐circularly polarized light. Measurement of mirror images of the CD spectrum is commonly used to determine the enantiomeric purity of small molecules. The measurement of the change, and sometimes loss, of optical activity measured in the spectral region of the chiral chromophores can be used to determine and understand the denaturation of a folded protein as the chirality changes with the change in gross structural features associated with the folding. We focus particularly in this chapter on the influence of metals on the chiral properties of proteins. Metal binding results in changes in molecular and supramolecular conformations readily measured under metal‐based spectral bands. In cases for which the folding of the protein is almost entirely metal‐induced, the CD spectrum becomes an extremely sensitive marker for structural change as a function of metal loading allowing both the stoichiometry of metal binding and the coordination geometry to be proposed. Measurement of the chirality of a molecule is easy in the region 190–1000 nm as several relatively inexpensive instruments provide high sensitivity. Time‐resolved CD spectral data are also readily achievable using stopped‐flow devices. Measurement in the infrared regions is also popular and provides invaluable information; instruments can now be purchased “off the shelf”. The new growth area is the use of synchrotron radiation as the light source allowing CD spectral data to be measured in all regions of the electromagnetic spectrum, but particularly, for energies higher than 50 000 cm −1 (below 200 nm).

show abstract

A New Mechanism for Metal Ion-assisted Interchain Helix Assembly in a Naturally Occurring Peptide Mediated by Optimally Spaced γ-Carboxyglutamic Acid Residues

Cited by 33 publications

References 49 publications

Helix-Helix Interactions between Homo- and Heterodimeric γ-Carboxyglutamate-containing Conantokin Peptides and Their Derivatives

Helix-Helix Interactions between Homo- and Heterodimeric γ-Carboxyglutamate-containing Conantokin Peptides and Their Derivatives

Stapling Mimics Noncovalent Interactions of γ-Carboxyglutamates in Conantokins, Peptidic Antagonists of N-Methyl-d-Aspartic Acid Receptors

Circular Dichroism ( CD ) Spectroscopy

Contact Info

Product

Resources

About