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3-Methylhexane is a branched hydrocarbon with two enantiomers. [2] It is one of the isomers of heptane . The molecule is chiral , and is one of the two isomers of heptane to have this property, the other being its structural isomer 2,3-dimethylpentane .
An unnatural base pair (UBP) is a designed subunit (or nucleobase) of DNA which is created in a laboratory and does not occur in nature. DNA sequences have been described which use newly created nucleobases to form a third base pair, in addition to the two base pairs found in nature, A-T (adenine – thymine) and G-C (guanine – cytosine).
The bonds between various bases are well defined because of their rigid and planar shape. The spatial interactions between the two bases can be classified in 6 rigid-body parameters or intra-base pair parameters (3 translational, 3 rotational) as shown in Figure 4. [63] These parameters describe the base pairs' three dimensional conformation.
However, the three hydrogen atoms are repelled by the electron lone pair in a way that the geometry is distorted to a trigonal pyramid (regular 3-sided pyramid) with bond angles of 107°. In contrast, boron trifluoride is flat, adopting a trigonal planar geometry because the boron does not have a lone pair of electrons.
Right: DNA strand intercalated at three locations (black areas). In biochemistry, intercalation is the insertion of molecules between the planar bases of deoxyribonucleic acid (DNA). This process is used as a method for analyzing DNA and it is also the basis of certain kinds of poisoning. Ethidium intercalated between two adenine-thymine base ...
As usual, a weaker acid has a stronger conjugate base. Examples of Lewis bases based on the general definition of electron pair donor include: simple anions, such as H − and F −; other lone-pair-containing species, such as H 2 O, NH 3, HO −, and CH 3 −; complex anions, such as sulfate; electron-rich π-system Lewis bases, such as ethyne ...
These purine-pyrimidine pairs, which are called base complements, connect the two strands of the helix and are often compared to the rungs of a ladder. Only pairing purine with pyrimidine ensures a constant width for the DNA. The A–T pairing is based on two hydrogen bonds, while the C–G pairing is based on three. In both cases, the hydrogen ...
[1] [2] [3] In addition to π-stacking between the aromatic regions of the intercalator and the nitrogenous bases of DNA, intercalation is stabilized by van der Waals, hydrophobic, electrostatic, and entropic interactions. [2] This ability to bind to specific DNA base pairs allows for potential therapeutic applications of metallo-intercalators.