## 2 The Selective Energy Transfer (SET) Theory
### COS and Resonance Conditions
** The tetrahedral structure of the nitrogen (indicated in Schemes 1 and 2) is made up by one metal atom (M) and one carbon atom (C), next neighbor to the carboxylate group (cf. Figure 4). In order to indicate the spatial (tetrahedral) arrangement, a plus sign indicates that the atom group is positioned above the NHH plane. Likewise, a minus sign indicates a position below that plane. **(c) The wagging effect. ** The figure illustrates how the two H atoms rise above the NHH plane (also here indicated by plus-sign and in red color) at a highly activated wagging vibration. One can also easily distinguish that the left-side hydrogen atom can form part of a tilting CHM plane into which the nitrogen atom can intrude. (This plane is indicated by double-drawn red lines between the atoms concerned.) The other H atom is distinctly placed outside the tilting CHM plane. As described in the text, this means that the N atom develops three sp2 orbitals that keeps the CHM plane together. **(d) At high excitation, the nitrogen atom will be unable to bind four atoms. ** The consequence of this will be that one hydrogen atom (marked in yellow) is set free. Scheme 1 illustrates that the role of the metal ion--besides achieving the best possible resonance conditions--is to create order between the two amino acid molecules; we name them as amino acid No. 1 and amino acid No. 2, respectively. The importance of metal atoms being present has been emphasized experimentally by [PERSON], [PERSON], [PERSON], and [PERSON] [25; 26]. One might note that the incoming amino acid (No. 2) has supposedly not formed a regular chelate, but hinges on the strong M-N bond, thus exposing its OH group for attack from the H atom of the \"No. 1\" NH2 group. As it is supposed that this reaction was happening at the verge of a volcanic vent, where metal sulfides (FeS or NiS [26]) had been precipitated over time, it is no surprise that the possibility of bonding ligands to a free metal ion was severely sterically limited. Therefore, the unbonded C-OH group swings open to an attack from a free H atom (Figure 4). When all this has happened, two alternative reactions might further take place: either the metal-carboxylate bond can split and a dimer, mono-peptide will form (Scheme 1), or the system keeps the original metal-carboxylate bond intact and forms a new chelate--this time with the recently formed M-NH2 group as the bonding partner (vide Scheme 2). The approach of a third amino acid makes possible the creation of a second peptide group. In principle, this procedure can go on in many steps, thus forming polypeptides. Such molecules are considered to be important building blocks for the emergence of life (e.g., [5]). One crucial question remains to be commented upon: Why is it only one of the two amino groups in Scheme 1 that responds to the infrared radiation that emits from the COS catalyst? Obviously, it is the one -NH2 group that first responds to this radiation that we observe, but why is there a difference? We suggest that the amino acid that reacts is the one that has a -COOH group firmly bonded to the metal atom as COO\({}^{-}\). It is the -NH2 group of the strong chelate that responds to the IR radiation and consequently releases one hydrogen atom. It is this free hydrogen atom that attacks the -OH group of the other amino acid. This is lightly indicated in the drawings of Scheme 1, and made more visible in Figure 4. Thus, it seems that a metal atom is crucial in this context [25], giving a strong resonance between the vibrational frequencies. Figure 4: The situation of binding between one copper ion and two amino acids just before the reaction to form a peptide bond. The strong bonds are designated in green color.