... The anchoring of a- carboxylateand a- amino group in the external aldimine definesautomatically the positions of the a- proton and the sidechain of any bound amino ac id. The lability of the a- protonobserved ... N.N. & Braunstein, A. E. (1947)Labilization of a- hydrogen of amino acids under the action of aminoferase. Biokhimia 12, 556–568 (in Russian).2. Esaki, N., Nakayuma, T., Sawada, S., Tanaka, ... The mechanism of a- proton isotope exchange in amino acids catalysedby tyrosine phenol-lyase1What is the role of quinonoid intermediates?Nicolai G. Faleev1, Tatyana V. Demidkina2, Marina...