Hexacyclo[10,3,1,02,10,,03,7,06,15,09,14]hexadecane; an ethanocongressane

Rao, S. T.; Sundaralingam, M.; Ōsawa, Eiji; Wiskott, E.; Schleyer, P. von R.

doi:10.1039/c29700000861

Cited by 15 publications

(18 citation statements)

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“…This effect has already been pointed out by Sundaralingam & Jensen (1965), Singh (1965), Rao & Sundaralingam (1970) and Prusiner et al (1973). This effect has already been pointed out by Sundaralingam & Jensen (1965), Singh (1965), Rao & Sundaralingam (1970) and Prusiner et al (1973).…”

Section: Molecular Structurementioning

confidence: 58%

The crystal and molecular structures of oxoformycin B and formycin, B

Koyama¹,

Nakamura²,

Umezawa³

et al. 1976

Acta Crystallogr Sect B

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813Oxoformycin B, Ct0HI206N4, crystallizes in the orthorhombic space group P212121 with a= 7.756 (6), b= 21.313 (15), c= 6.831 (5) A, Z= 4, and formycin B, C10H12OsN4, in the monoclinic space group P21 with a= 13.493 (10), b=6.257 (6), c=6"705 (5) A, ,8=99.71 (7) °, Z=2. Both crystal structures were solved by the direct method and refined by the least-squares method to R values of 0.04 including H atoms. In oxoformycin B, the conformation of the C-glycosyl bond is syn with a Z angle of -164-1 ° and that of the ribofuranose group is C(Y)-endo with a gauche-gauche (gg) conformation about the

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Section: Molecular Structurementioning

confidence: 58%

The crystal and molecular structures of oxoformycin B and formycin, B

Koyama¹,

Nakamura²,

Umezawa³

et al. 1976

Acta Crystallogr Sect B

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“…A similar conclusion has been reached from molecular model studies. 22 It is seen that potential energy rapidly increases in the syn region (Fig. 5a) (x >210°) for values of ,b near 60" due to the strong steric repulsion between the atoms of the base and the phosphate group (Fig.…”

Section: With C(2')-end0 Puckering For Ribosementioning

confidence: 97%

Correlation between the backbone and side chain conformations in 5′‐nucleotides. The concept of a ‘rigid’ nucleotide conformation

1973

Self Cite

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SynopsisConformational energies of the 5'-adenosine monophosphate have been computed as a function of x and $, of the torsion angles about the side-chain glycosyl C( lf)-N(9) and of the main-chain exocyclic C(4')-C(5 ') bonds by considering nonbonded, torsion, and electrostatic interactions. The two primary modes of sugar puckering, namely, C(2')-mdo and C(3')-ado have been considered. The results indicate that there is a striking correlation between the conformations about the side-chain glycosyl bond and the backbone C(4')-C(5') bond of the nucleotide unit. It is found that the anti and the gauche-gauche (99) conformations about the glycosyl and the C(4'tC(Sf) bonds, respectively, are energetically the most favored conformations for 5'-adenine nucleotide irrespective of whether the puckering of the ribose is C(2')-endo or C(3')-ado. Calculations have also shown that the other common 5 '-pyrimidine nucleotides will show similar preferences for the glycosyl and C(4')-C(5') bond conformations. These results are in remarkable agreement with the concept of the "rigid" nucleotide unit that has been developed from available data on mononucleotides and dinucleoside monophosphates. It is found that the conformational 'rigidity' in 5'-nucleotides compared with t.hat of nucleosides is a consequence of, predominantly, the coulombic interactions between the negatively charged phosphate group and the base. The above result permits one to consider polynucleotide conformations in terms of a "rigid" C(2')-mdo or C(3')-mdo nucleotide unit with the major conformational changes being brought about by rotations about the P-0 bonds linking the internucleotide phosphorous atom. It is predicted that the anti and the gg conformations about the gly cosy1 and the C(4')-C(5') bonds would be strongly preferred in the mononucleotide components of diff erent purine and pyrimidine coenzymes and also in the nucleotide phosphates like adenosine di-and triphosphates.

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“…In this respect, one can note that the major difference between cAMP and its analogues on the one hand, and cGMP and its analogue cIMP on the other, is that in the former the N ( l ) atom is deprotonated and a hydrogen bond acceptor and the 6-NH2 group is a hydrogen bond donor, whereas in the latter, the N( 1) atom is protonated and a hydrogen bond donor and the 6-keto group is a hydrogen bond acceptor. Moreover, it is known that the syn conformation in free nucleotides is promoted by intramolecular hydrogen bonding (Rao & Sundaralingam, 1970;Plochocka et al, 1977). Thus, it may not be unreasonable to postulate that hydrogen bonding between a -NH-C(=O) fragment of the protein backbone and the N ( l ) atom and 6-NH2 group of the adenine ring in a Watson-Crick basepair-like structure, the adenine N ( 1) atom hydrogen bonding with the peptide N H group and the adenine 6-NH2 group with the peptide C = O group, could be responsible for the selection of the syn conformation of cAMP and its analogues when bound to CRP.…”

Section: ' H N M R S T U D Y O F E C O L I C a M P R E C E P T O R mentioning

confidence: 99%