Structural stability energetics

The secondary structures we have described here are all found commonly in proteins in nature. In fact, it is hard to find proteins that do not contain one or more of these structures. The energetic (mostly H-bond) stabilization afforded by a-helices, /3-pleated sheets, and /3-turns is important to proteins, and they seize the opportunity to form such structures wherever possible. 

In a review, Gorelik51 has shown that magnetic, structural, and energetic properties are determined by the electronic structure of cyclic conjugated systems, which are stabilized by a cyclic delocalization of electrons. Chemical reactivity cannot serve satisfactorily as a general criterion of aromaticity. 

TS B14 leads to the complex B15. Here all the incipient changes found in TS B14 have completed N1 has two N-H bonds and is essentially localized on Zr2 and the N-N bond is completely broken. In almost every aspect, B15 is an analogue to BIO of the previous reaction path. This is true even energetically B15 is 36.6 kcal/mol more stable than reactants (B1 + H2) and 79 kcal/mol below TS B14 in the Zr-P frozen geometries. For the unconstrained structures, the corresponding stabilities are 33.6 and 72.8 kcal/mol. The similarity in developments along the A (first H2) and B (second H2) reaction paths is very clear, both structurally and energetically. 

We would like to remind that all tubular structures are composed of 96 boron atoms, the same number of atoms in the elemental a-boron unit cell of boron crystals. The purpose is simply having clusters of the same size, in order to be energetically comparable. On one hand, a-boron is a real component existing in nature, and on the other hand, single-wall nanotubes so far have been predicted and also synthesized [15]. In this case we calculated the total B3LYP energies and determined the structure stability as follows = (nEi - E ) / n = Ei - E / n, where E is the... 

The stabilization energetics associated with both types of molecules have been probed by looking at factors, including temperature, that disrupt their three-dimensional structures, but do not break the bonds that keep their primary structure intact. It is believed that much information about the nature of the forces that hold the molecule in its three-dimensional structure can be gained by understanding under what conditions these forces can be overcome. 

Ionic strength influences are well known with respect to the rate and energetics of nucleic acid hybridization [17]. Charge and ionic radius are both important in terms of stabilizing the structure of the duplex as well as stabilizing the stem portion of the molecular beacon [17]. The stem structure stability was increased when a divalent cation was incorporated into the hybridization buffer solution [17]. It was reported that cations were best at stabilizing the duplex formed upon hybridization in the order Ca2+ > Mg2+ K+ > Na+. The ultimate detection limit of the sensor configuration was calculated to be 1.1 nM [17]. 

Klostermeier, D., and Millar, D. P. (2001). Tertiary structure stability of the hairpin ribozyme in its natural and minimal forms Different energetic contributions from a ribose zipper motif. Biochemistry 40, 11211—11218. 

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