Biomolecular structure chemical probing, hydroxyl radical probing, nucleotide analog interference mapping (NAIM), and in-line probing. Protein and nucleic acid structures can be determined using either nuclear magnetic resonance spectroscopy (NMR) or X-ray crystallography or single-particle cryo electron microscopy (cryoEM). The first published reports for DNA (by Rosalind Franklin and Raymond Gosling in 1953) of A-DNA X-ray diffraction patterns—and also B-DNA—used analyses based on Patterson function transforms that provided only a limited amount of structural information for oriented fibers of DNA isolated from calf thymus. An alternate analysis was then proposed by Wilkins et al. in 1953 for B-DNA X-ray diffraction and scattering
Triple-stranded DNA Triple-stranded DNA Triple-stranded DNA (also known as H-DNA or Triplex-DNA) is a DNA structure in which three oligonucleotides wind around each other and form a triple helix. In triple stranded-DNA, one strand binds to a B-form DNA (Watson–Crick base-pairing) through Hoogsteen base pair or reversed Hoogsteen hydrogen bonds. A thymine (T) nucleobase can bind to a Watson–Crick base-pairing of T-A by a Hoogsteen hydrogen bond. The thymine attaches to the adosine (A) of the origin double stranded DNA to create a T-A*T base-triplet. In acidic conditions, a protonated cytosine, represented as C+, can form a base-triplet with a C-G pair