Abstract The crystal structure of [(N-salicylidene-ᴅ,ʟ-glutamato)(pyridine)]copper(II), a model for vitamin B6-amino acid-related metal complexes, has been determined by an X-ray analysis. A close examination of the structural data on this and other related complexes combined with quantum-chemical (INDO/2) calculations enabled us to make a clear distinction between two mechanisms proposed earlier for metabolic reactions of amino acids catalyzed by the vitamin B6 (or salicylaldehyde)-metal system. The results are consistent with a transient formation of a carbinolamine species resulting from the addition of a solvent water or alcohol molecule to the Schiff base double bond, thus supporting the mechanism of the catalysis as proposed by Gillard and Wootton.
