protomolecule

proto- +‎ molecule

protomolecule (plural protomolecules)

1. A collection of unstably bound atoms that has the potential to form a molecule if the structure can shed sufficient energy.
   • 1991, Ezio Bussoletti, G. Strazzulla, Solid-state astrophysics: 27 June-7 July 1989, →ISBN, page 385:

     Molecular hydrogen is by the way a very difficult species to form in the gas phase by radiative association of H atoms, mainly because the protomolecule formed in this way is vibrationally highly excited and cannot get rid of the energy excess to enter inside the potential well and reach stability in a time short enough to avoid breaking.

   • 1998, Julián Chela Flores, F. Raulin, Exobiology, →ISBN, page 287:

     This is a consequence of the fact that the protomolecule, just formed in a high vibrational level, has to release quickly (roughly in a time comparable with its vibrational period) an energy excess of about four and a half electronvolt.

   • 2004, M. P. Bernstein, Space life sciences: steps toward origin(s) of life, page 6:

     As pointed out many years ago (see, for example, Duley and Williams, 1984), molecular hydrogen cannot form efficiently in the gas phase in the ISM, when H atoms are neutral and in the ground state, since three-body reactions are necessary to take out the excess energy quickly enough before the protomolecule falls apart.

2. A relatively simple molecule from which a more complex molecule is derived.
   • 1912, George Frederick Shrady, Thomas Lathrop Stedman, Medical Record:

     It is most probable that all matter is simply the allotropic expression of one element and that the protomolecule is the union of the positively and negatively electrified etheric corpuscle.

   • 1982, Canada Parlement House of Commons Standing Committee on Miscellaneous Estimates, Minutes of Proceedings and Evidence of the Standing Committee on Miscellaneous Estimates:

     Another example is the technique developed at NRC for synthesizing the insulin protomolecule.

   • 2001, Optical Technologies in Biophysics and Medicine, page 114:

     The local structure seen in Figure 3 may in fact be the entire structure of a fundamental melanin protomolecule.

• protomolecular