N-conformation

Volkov, S.N. Conformational transitions and the mechanism of transmission of long-range effects in DNA. Preprint ITP-88-12E, Kiev (1988) 22 Krumhansl, J.A., Alexander, D.M. Nonlinear dynamics and conformational exitations in biomolecular materials. In Structure and dynamics nucleic acids and proteins. (Clementi, E., Sarma, R.H., eds) Adenine Press, New York (1983) 61-80... 

In general, two related techniques may be used principal component analysis (PCA) and principal coordinate analysis (PCoorA). Both methods start from the n X m data matrix M, which holds the m coordinates defining n conformations in an m-dimensional space. That is, each matrix element Mg is equal to q, the jth coordinate of the /th conformation. From this starting point PCA and PCoorA follow different routes. 

The global sensitivity (Sensitivityx.a will be the average of the pairwise sensitivities computed for all possible pairs of N conformers, i.e. for N(N-l) pairs. 

Endredi, G., C.-M. Liegener, M. A. McAllister, A. Perczel, J. Ladik, and I. G. Csizmadia. 1994. Peptide Models 8. The Use of a Modified Romberg Formalism for the Extrapolation of Molecular Properties from Oligomers to Polymers. Polyalanine Diamide in Its Extended Like or (f3, or (C5)n Conformation. J. Mol. Struct. (Theochem) 306, 1-7. 

IV [79] which present respectively chains in trans-planar and in a non-helical (T6G2T2G2)n conformation. In form I (see Table 2), i.e., the stable form of sPP obtained under most crystallization conditions, the chains are packed with an alternation of right-handed and left-handed helices. On the contrary, in the somewhat less stable form II [80], all the helical chains share the same chirality. 

N. Conformational Analysis of Molecules in Solution (CAMSEQ). A problem of long standing in chemistry has been to estimate the relationship between the conformation of a molecule in the crystal, as measured by X-ray methods, with that in solution where barriers to rotation are greatly reduced. A sophisticated program set for Conformational Analysis of Molecules in Solution by Empirical and Quantum-mechanical methods (CAMSEQ) has been developed for this purpose by Hopfinger and co-workers [l2] at Case Western Reserve University. 

The ylides preferentially adopt Ca—S and Ca—N conformations in which the lone-pair orbital at the Ca atom is periplanar to the S=0 bond, and that at the N atom is periplanar to the Ca—Ph bond. An important factor in the determination of the Ca—S and N—S energy minimum conformations of the ylides is the orthogonality of the lone pairs at the Ca and N atoms. 

SAR. Introduction of a (N)-methanocarba modification to NEC A in 56 increased the hA3AR binding affinity by sixfold. Thus, the (N) conformation is confirmed to be highly preferred over the (S) conformation for binding at the A3AR, for a range of structures of multiply modified nucleoside derivatives. 

The values in Table II were obtained by analysis of the A3A 3 XX spin system observed in the 2 P and spectra, using F F homonuclear INDOR experiments. The dispersion in the J(PP) values is probably due to a more important contribution of the txa.n conformation to the conformational populations in the B1C40 and d,t isomers. The 2J(PCF3) values show also marked differences between the m 60 and the d,Z isomer but they will be difficult to use as a stereochemical probe as long as there is no reliable way to identify these isomers. 

Table n. Conformational Equilibria of Monosubstituted Cyclohexanes in Solution... 

S n conformational entropy of a globule witit the given density distribution n( ). 

More recently, Kronman and Bratcher (1984) found that Tb(III) displaces Ca(II) in a-lactalbumin. With increasing concentration, Tb(III) binds to a second site with a concomitant decrease in affinity for metal ion binding to the first site, resulting in a decreased stability of the native conformation (or N) conformer, and thus renders more favorable the... 

Lucero, M. J., Houk, K. N. Conformational Transmission of Chirality The Origin of 1,4-Asymmetric Induction in Michael Reactions of Chiral Imines. J. Am. Chem. Soc. 1997, 119, 826-827. 

In RNA, most residues have Ch -endo sugar puckers (N-conformations) with small 3/hi H2 coupling (<2-3Hz) and with the corresponding Hl -H2 cross-peaks not observed in homonuclear 2D COSY or TOCSY spectra. These cross-peaks are observed only for flexible residues and residues locked in the S-conformations the presence or absence of TOCSY Hl -H2 cross-peaks is often used for qualitative estimation of sugar puckers. 

Rearrangements of a-substituted cyclopropylmethyl radicals afford mixtures of the (E)-and (Z)-butenyl radicals usually with a preponderance of the Z-isomer. This stereoselectivity is probably a consequence of the higher proportion of the a /-conformer compared to the j n-conformer, the former being lower in energy for steric reasons i.e. nonbonded interactions between the substituent and ring hydrogens are less important. The -alkene is also thermodynamically more stable than the Z-alkene. ... 

The (Gibbs) free energy level of a solvated electron in a solution in equilibrium with the electrode is equal to the level of electrochemical potential of electron in metal p. We shall call this equilibrium electrode the electron electrode. Suppose that we are concerned with a standard solution (1 mol/1) and hence the standard potential E°. In this case, w determined at E° and corrected for the entropy of delocalized electrons (at n conforming to 1 mol/1) is the difference between standard chemical potentials of localized and delocalized electrons. 

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