Biotechnology. Atypical aminoacids XI

This paper tries to reconstitute the evolution of th formation of the alpha -amino-acidic structure. In this direction are presented two most important transitions; from L-P(O) to LPN) (see the text) and from M-3 to M-4 (ie fr om the ternary basic metabolism to the quaternary basic metabolism). The or igins of at least one from these two transitions seems to be the alpha isom erical phenomenon. This paper promotes the idea that alpha-hydroxy-acidic s tructure is the ancestor of the alpha-amino-acidic structure, and from this point of view rises the question: why the evolution eliminated the alpha-h ydroxy-acidic structure for the alpha-amino-acidic structure? Together with an evolutionary pattern for the formation of the alpha-aminoacidic structu re the answer is presented This pattern cosists in a succesion of three evo lutive moments (hydroxylic --> acrylic --> cetonic) who are presented and b riefly characterised.