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Chemical structure of an LNA monomer an additional bridge bonds the 2' oxygen and the 4' carbon of the pentose. A locked nucleic acid (LNA), also known as bridged nucleic acid (BNA), [1] and often referred to as inaccessible RNA, is a modified RNA nucleotide in which the ribose moiety is modified with an extra bridge connecting the 2' oxygen and 4' carbon.
The conformation of G is syn, C2'-endo; for C it is anti, C3'-endo. [13] A linear DNA molecule having free ends can rotate, to adjust to changes of various dynamic processes in the cell, by changing how many times the two chains of its double helix twist around each other. Some DNA molecules are circular and are topologically constrained.
L-Ribose Fischer Projection. Ribose is a simple sugar and carbohydrate with molecular formula C 5 H 10 O 5 and the linear-form composition H−(C=O)−(CHOH) 4 −H. The naturally occurring form, d-ribose, is a component of the ribonucleotides from which RNA is built, and so this compound is necessary for coding, decoding, regulation and expression of genes.
A bridged nucleic acid (BNA) is a modified RNA nucleotide. They are sometimes also referred to as constrained or inaccessible RNA molecules.BNA monomers can contain a five-membered, six-membered or even a seven-membered bridged structure with a "fixed" C 3 '-endo sugar puckering. [1]
H/ACA snoRNAs also contain conserved sequence motifs known as H box (consensus ANANNA) and the ACA box (ACA). Both motifs are usually located in the single-stranded regions of the secondary structure. The H motif is located in the hinge and the ACA motif is located in the tail region; 3 nucleotides from the 3′ end of the sequence. [11]
In one study, the characteristic C3'-endo pucker is found on the first three sugars of the DNA strand, while the last three sugars have a C2'-endo pucker, like B-DNA. [2] These intermediates can form in aqueous solutions when the cytosine bases are methylated or brominated, altering the conformation.
Glucal in its preferred half-chair conformation. Glycals can be formed as pyranose (six-membered) or furanose (five-membered) rings, depending on the monosaccharide used as a starting material to synthesize the glycal. Glycals can also be classified as endo-glycals or exo-glycals. A glycal is an endo-glycal when the double bond is within the ring.
In organic chemistry, endo–exo isomerism is a special type of stereoisomerism found in organic compounds with a substituent on a bridged ring system. [1] The prefix endo is reserved for the isomer with the substituent located closest, or " syn ", to the longest bridge.