Ribonucleic acids hydrogen bonding

A solution leading to a successful algorithm was recently found for the folding of ribonucleic acid (RNA) [36], Natural RNA polymers (figure C2.14.1) are mainly made up from four different bases . A, C, G and U. As with DNA, multiple hydrogen bonding favours the fonnation of G-C and A-U pairs [16, 37, 38] which leads to the appearance of certain characteristic stmctures. Loop closure is considered to be the most important folding event. 

The nucleic acids known as deoxyribonucleic acid (DNA) are the molecules that store genetic information. This information is carried as a sequence of bases in the polymeric molecule. Remarkably, the interpretation of this sequence depends upon simple hydrogen bonding interactions between base pairs. Hydrogen bonding is fundamental to the double helix arrangement of the DNA molecule, and the translation and transcription via ribonucleic acid (RNA) of the genetic information present in the DNA molecule. 

The above-mentioned purine-pyrimidine base-pairing scheme consists, as it is well known, of hydrogen bonding between specific, complementary base pairs, namely, adenine-thymine [or uracil in ribonucleic acid (RNA)] and guanine-cytosine (Fig. 1) (shorthand notations A-T or A-U and G-C). The specificity of the bonding concerns both this exclusiveness and the steric arrangement which is... 

Ribonuclease, the enzyme that hydrolyzes ribonucleic acids (Chap. 7), contains four disulfide bonds that help to stabilize its conformation. In the presence of 6 M guanidine hydrochloride, to weaken hydrogen bonds and hydrophobic interactions, and 1 mM mercaptoethanol, to reduce the disulfide bonds, all enzymatic activity is lost, and there is no sign of residual secondary structure. On removing the guanidine hydrochloride by dialysis or gel filtration, enzymatic activity is restored, the native conformation is regained, and correct disulfide bonds are reformed. 

The bases found in RNA (ribonucleic acid) are the purine heterocyclics adenine (6-aminopurine) and guanine (2-amino-6-oxypurine) and their complementary pyrimidine bases uracil (2,4-dioxypyrimidine) and cytosine (2-oxy-4-aminopyrimidine), respectively (Section 1, Appendix). In RNA double-stranded duplexes adenine (A) base-pairs with uracil (U) via two hydrogen bonds (A=U) and guanine base-pairs with cytosine (C) via 3 hydrogen bonds (G=C). Adenine forms the nucleoside adenosine by an N-glycosidic link with the... 

Polynucleotides include ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). Under physiological conditions, DNA normally exists in the p-form, which consists of two antiparallel strands the Watson-Crick double helix. Interstrand hydrogen bonding connects the two strands. An adenosine in one strand can hydrogen bond with a thymine in the second, and a guano-sine can hydrogen bond with a cytosine in the other strand. The strands must be antiparallel 32, 52, 63, 64. 

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