Abstract: These studies concern the catalytic activity of clays on amino acids, particularly tyrosine. Polyhydric phenols were included to help understand the tyrosine reactions.
Below pH 3, tyrosine is adsorbed on clay minerals by cation exchange. Above pH 3, oxidative degradation of tyrosine occurs, the L-isomer altering more rapidly. The rate of alteration depends upon the particular clay mineral, surface modifications such as polyphosphate treatment, heating, and the presence of copper, aluminium, and mercury. A free radical mechanism is proposed for the alteration.