• structural
  • From the very early stages of structural studies of DNA by X-ray diffraction and biochemical means, molecular models such as the Watson-Crick nucleic acid double helix model were successfully employed to solve the 'puzzle' of DNA structure, and also find how the latter relates to its key functions in living cells. (wikipedia.org)
  • atoms
  • Macrocyclic stereocontrol refers to the directed outcome of a given intermolecular or intramolecular chemical reaction, generally an organic reaction, that is governed by the conformational or geometrical preference of a carbocyclic or heterocyclic ring, where the ring containing 8 or more atoms. (wikipedia.org)
  • molecular structure
  • X-ray crystallography, neutron diffraction and electron diffraction can give molecular structure for crystalline solids based on the distance between nuclei and concentration of electron density. (wikipedia.org)
  • Molecular geometries are best determined at low temperature because at higher temperatures the molecular structure is averaged over more accessible geometries (see next section). (wikipedia.org)
  • 596. Subramanian E., Molecular structure of acid-proteases. (ximicat.com)
  • Atomic and molecular structure. (ucalgary.ca)
  • It was only in 1918 when Ernst Mohr, based on the molecular structure of diamond that had recently been solved using the then very new technique of x-ray crystallography, was able to successfully argue that Sachse's chair was the pivotal motif. (wikipedia.org)
  • A cocaine analogue is a (usually) artificial construct of a novel chemical compound from (often the starting point of natural) cocaine's molecular structure, with the result product sufficiently similar to cocaine to display similarity in, but alteration to, its chemical function. (wikipedia.org)
  • reaction
  • 1. [a] Formulate two Zimmerman-Traxler transition structures for the reaction of benzaldehyde with the Z-enolate shown on the right: [b] Assuming that product selectivity will be based upon the relative energies of the two transition structures, predict the favored pathway. (coursehero.com)
  • Significantly, even small conformational preferences, such as those envisioned in floppy macrocycles, can profoundly influence the ground state of a given reaction, providing stereocontrol such as in the synthesis of miyakolide. (wikipedia.org)
  • energy
  • In general, the substituents exhibit preferences for equatorial placement, except for the lowest energy structure (pseudo A-value of -0.3 kcal/mol in figure below) in which axial substitution is favored. (wikipedia.org)
  • Timing and energy are also factors in isomerism. (britannica.com)
  • secondary
  • Two new RCCS sets are presented here, determined in dimethyl sulfoxide (DMSO) and chloroform:methanol:water (4:4:1 by volume) at 298 K. A web-based program, CS-CHEMeleon, has been implemented to determine the accuracy of secondary structure assessment by calculating and comparing Δδ values for various RCCS datasets. (springer.com)
  • Despite obvious RCCS variations between datasets, prediction of secondary structure was consistently similar. (springer.com)
  • Strikingly, predictive accuracy seems to be most dependent upon the type of secondary structure, with helices being the most accurately predicted by Δδ values using five different RCCS tables. (springer.com)
  • Protein secondary structure can be described in terms of the dihedral angles φ, ψ and ω of the protein backbone. (wikipedia.org)
  • Multiple prolines and/or hydroxyprolines in a row can create a polyproline helix, the predominant secondary structure in collagen. (wikipedia.org)
  • bonds
  • In general, stereoisomers contain double bonds that cannot rotate, or they may contain ring structures, where the rotation of bonds is restricted or prevented. (wikipedia.org)