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.

   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.

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

   2 more examples

   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.

   1991, Ezio Bussoletti, G. Strazzulla, Solid-state astrophysics: 27 June-7 July 1989, →ISBN, page 385

   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.

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

2. A relatively simple molecule from which a more complex molecule is derived.

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

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

   2 more examples

   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.

   1912, George Frederick Shrady, Thomas Lathrop Stedman, Medical Record

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

   2001, Optical Technologies in Biophysics and Medicine, page 114