Is the parallel or antiparallel beta-sheet more stable? A semiempirical study.

C Gailer; M Feigel

doi:10.1023/a:1007908728919

Home/Archive/PubMed

PubMed · 9263854

Is the parallel or antiparallel beta-sheet more stable? A semiempirical study.

C Gailer·M Feigel

View original source ↗Export metadata ↓

Abstract

The geometry and energy of parallel and antiparallel peptidic beta-sheets have been calculated using AM1. beta-Sheets composed of two peptide chains of up to 11 amino acid residues (Ala and Gly) and the dimers of cyclooctapeptides are used as model systems. The enthalpic difference between the parallel and the antiparallel arrangement is calculated to be very small, as it is found experimentally for the cyclic systems. The coordinates of the calculated structure of the cyclooctapeptide dimer 1 (cyclo-D,L-(Ala)8) have an rms deviation of only 0.223 A to the coordinates of the corresponding cyclopeptide obtained by X-ray analysis.

Explore related subjects

Dimerization Hydrogen Bonding Models, Molecular Peptides, Cyclic Protein Structure, Secondary Proteins Thermodynamics Journal Article

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

C Gailer, M Feigel. 1997. Is the parallel or antiparallel beta-sheet more stable? A semiempirical study.. https://doi.org/10.1023/a%3A1007908728919

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Photosynthetic reaction center mimicry of a "special pair" dimer linked to electron acceptors by a supramolecular approach: self-assembled cofacial zinc porphyrin dimer complexed with fullerene(s).

Biomimetic bacterial photosynthetic reaction center complexes have been constructed using well-defined self-assembled supramolecular approaches. The "special pair" donor, a cofacial porphyrin dimer, was formed via potassium ion induced dimerization of meso-(benzo-[15]crown-5)porphyrinatozinc. The dimer was subsequently self-assembled with functionalized fullerenes via axial coordination and crown ether-alkyl ammonium cation complexation to form the donor-acceptor pairs, mimicking the noncovalently bound entities of the photosynthetic reaction center. The adopted self-assembly methodology yielded supramolecular complexes of higher stability, with defined geometry and orientation. Efficient forward electron transfer from the singlet excited zinc porphyrin dimer to the fullerene entity and relatively slow reverse electron transfer, important steps in the photosynthetic light energy conversion have been achieved in these novel biomimetic model systems.

Dimerization↗

PubMed2007

The R2464C missense mutation in the von Willebrand factor gene causes a novel abnormality of multimer electrophoretic mobility and falls into the subgroup of type 2 von Willebrand disease 'unclassified'.

Explore the source record for details and available documents.

Dimerization↗

PubMed2006

Dimerization and double proton transfer-induced tautomerism of 4(3H)-pyrimidinone in solution studied by IR spectroscopy and quantum chemical calculations.

The tautomerism and dimerization of 4(3H)-pyrimidinone (4(3H)Pyr) in carbon tetrachloride (CCl4) and chloroform (CHCl3) solutions were investigated using IR spectroscopy and quantum chemical calculations. The observed IR spectra in the NH and OH stretching regions clearly revealed the predominance of the keto tautomer in both solvent systems. The enol form only exists in a very small proportion in the CCl4 solution. The tautomeric constant for the two monomers KT[OH/NH] = 0.012 and DeltaE = 2.62 kcal/mol were estimated at 25 degrees C. This result was supported by the self-consistent reaction field/polarizable continuum (SCRF/PCM) calculation at the MP4(full, SDQ)/aug-cc-pVDZ level, which predicted DeltaE = 3.06 kcal/mol in CCl4. In the C=O stretching region, two bands were observed, suggesting the coexistence of two keto structures at equilibrium. The calculated IR spectra indicated that the bands at 1711 and 1675 cm(-1) arise from the keto monomer and keto-keto (KK) ring dimer, respectively. At elevated temperature, the populations of both the keto and enol monomers increased for the CCl4 solution. The present study revealed that the keto <--> enol tautomerization does not occur in the isolated monomer molecule. The double proton transfer (DPT) reaction in the KK ring dimer presumably plays a substantial role in the population increase of the enol monomer. To our knowledge, this may be the first observation of the tautomerization in a model base pair via the temperature-induced ground-state DPT reaction under a nonpolar liquid environment reported so far. This tautomerism can serve as a mimic circumstance for the spontaneous mutations induced by proton transfer in the DNA base pairs.

Dimerization↗