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They are all at least partly exposed to the solvent around thyroglobulin, and the side chains of the donor–acceptor pairs formed by these residues face each other in an approximately antiparallel configuration.

On rare occasions the spins of the protons and electrons in neutral hydrogen atoms flip from being parallel to antiparallel, emitting a photon at a frequency of 1.4 gigahertz—the so-called 21-centimter radiation.

In most cases, spins of neighbouring atoms tend to align parallel or antiparallel to each other, resulting in ferromagnets or antiferromagnets, respectively.

Class 6 contains antiparallel, face-to-back, up–up structures; class 7 contains antiparallel, face-to-face up–down structures; and, class 8 contains antiparallel, face-to-face, up–down structures.

Each protomer contributes an intertwined helical pair that bends in a left-handed helical 180° turn over the length of the channel, forming an antiparallel coiled coil in the upper and middle part of the pore.