Stereochemistry of nucleic acids and their constituents. XVIII. Conformational analysis of .alpha. nucleosides by x-ray crystallography

1971 ◽  
Vol 93 (24) ◽  
pp. 6644-6647 ◽  
Author(s):  
M. Sundaralingam
Keyword(s):  
Nucleic Acids ◽  
Conformational Analysis ◽  
X Ray ◽  
X Ray Crystallography

scholarly journals The dimensions and shapes of the furanose rings in nucleic acids

1972 ◽  
Vol 130 (2) ◽  
pp. 453-465 ◽  
Author(s):  
S. Arnott ◽  
D. W. L. Hukins
Keyword(s):  
Nucleic Acids ◽  
Model Building ◽  
Molecular Model ◽  
Relative Orientation ◽  
Ring Conformation ◽  
Mean Values ◽  
Pyrimidine Base ◽  
X Ray ◽  
X Ray Crystallography ◽  
Ring Puckering

A survey was made of the geometry of furanose rings in β-nucleotides and β-nucleosides (as monomers related to nucleic acids) for which structures have been determined by X-ray crystallography. Mean values, and estimated standard deviations from them, were calculated for bond-lengths, bond-angles and conformation-angles. For parameters with values dependent on ring-puckering, separate calculations were made for each ring type. (The rings are puckered in one of three conformations: C-2- or C-3-endo or C-3-exo; C-2-exo has not been observed.) The results were used to compute standard furanose rings with C-2-endo, C-3-endo and C-3-exo conformations for use in nucleic acid molecular model-building. The survey also showed that the only other conformation-angle in nucleotides dependent on the furanose ring conformation corresponds to the relative orientation of the purine (or pyrimidine) base and the ring.

scholarly journals Structural Effects of meso-Halogenation on Porphyrins: meso-Xn-ABCD Macrocycles

2021 ◽  
Author(s):  
Keith J Flanagan ◽  
Maximilian Paradiz Dominguez ◽  
Zoi Melissari ◽  
Hans-Georg Eckhardt ◽  
René M Williams ◽  
...  
Keyword(s):  
Conformational Analysis ◽  
Crystal Engineering ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Normal Coordinate ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Past ◽  
Meso Position

The use of halogens in the crystal engineering of porphyrin scaffolds has been a topic of strong interest over the past decades. Previously, this was focused on the introduction of a variety of halogens on the meso-phenyl groups of the porphyrin. However, investigations into the effects of direct halogenation of porphyrins at the meso-position on their crystalline architectures have not been conducted to date. Herein we have characterized a series of direct meso-halogenated porphyrins using single crystal X-ray crystallography. This is accompanied by a detailed conformational analysis of all deposited meso-halogenated porphyrins in the CCDC. In this study we have used the Hirshfeld fingerprint plots together with normal-coordinate structural decomposition and determined crystal structures to elucidate the conformation, present intermolecular interactions, and compare respective contacts within the crystalline architectures. Additionally, we have used density functional theory calculations to determine the structure of several halogenated porphyrins. This contrasts conformational analysis with existing X-ray structures and gives a method to characterize samples that are difficult to crystallize.

1. The roots of biochemistry

2021 ◽  
pp. 1-23
Author(s):  
Mark Lorch
Keyword(s):  
Nucleic Acids ◽  
20Th Century ◽  
19Th Century ◽  
Structural Biology ◽  
Ribonucleic Acid ◽  
Alcoholic Beverages ◽  
X Ray ◽  
X Ray Crystallography ◽  
History Of ◽  
The 19Th Century

This chapter traces the history of biochemistry, which is linked to the understanding of arguably the oldest uses of biotechnology—fermentation and the production of alcoholic beverages and cheese. In the 19th century, at the same time as the fermentation debates and enzymology flourished, the nature of proteins was under scrutiny. The chapter then considers the contribution that X-ray crystallography has made to structural biology. By the mid-20th century, the structures of the two massive molecular players, protein and nucleic acids (DNA along with ribonucleic acid), and their myriad roles were in place. It was becoming apparent that these were the fundamental molecular machines that marshal the chemistry within cells.

Sign in / Sign up

Export Citation Format

Share Document