Kristall- und Molekülstruktur von 3'-O-Acetyl-4-thiothymidin

Principles of Nucleic Acid Structure

“…The peptide group formed by Ca,-Na,-C-C" is antiperiplanar and projects straight from the five-membered sugar ring, with torsion angle Ha,-Ca,-Na,-C in syn-periplanar range. This particular atomic arrangement appears to be a characteristic feature of (planar) carboxyl or peptidyl groups attached to the Ca, carbon of furanoses-in 3 '-0acetylnucleosides, a similar situation is found (195,712,713). The conformation of the p-methoxyphenylalanyl moiety is not unusual, with torsion angles N-C,,-CrCy and Na,-C-C,,-C tl in the common extended (ap) and staggered (sc) ranges.…”

Participation in protein biosynthesis of transfer ribonucleic acid bearing altered 3'-terminal ribosyl residues

“…In fact, there is only one possible conformation in which both 2'and 3z-aminoacyl-tRNA isomers have the amino group in an identical position. Endo conformations of the carbonyl groups, in which the carbonyl oxygen points beneath the ribose ring, are excluded by the results of X-ray (Sundaralingam and Arora, 1969) and conformation analysis (Yathindra and Sundaralingam, 1973) of puromycin and acetyl nucleosides (Mathieson, 1965;Saenger and Suck, 1971). Taking these data into account, the sterically most favoured conformation for the aminoacyl residue of 2z-aminoacyl-tRNA or 3z-aminoacyl-tRNA is shown in Figure 11 (above).…”

Molecular orbital studies on the conformation of the terminal aminoacyladenosine moieties of tRNA

“…The formation of an intramolecular H-bond between this group and N3 of the adenine ring was forbidden because in the biological medium this group is bound through a phosphate link to the backbone of t-RNA. The ester group was considered planar (01 = 180 °) in agreement with X-ray results on the related 3'-0acetyl adenosine [12] and 3'-O-acetyl-4-thiothymidine [12]. Preselected values ofx 1 = 60 ° and 180 ° for the Ca-C t3 bond and of X 2 = 90 ° for the C~-C ~' bond were adopted.…”