Metabolism of l-Tyrosine to 4-Hydroxybenzaldehyde and 3-Bromo-4-Hydroxybenzaldehyde by Chloroplast-containing Fractions of Odonthalia floccosa (Esp.) Falk.

The biosynthesis of 4-hydroxybenzaldehyde and 3-bromo-4-hydroxybenzaldehyde from l-[U-(14)C]tyrosine has been demonstrated in chloroplast-containing fractions obtained by differential and isopycnic centrifugation from the marine red alga Odonthalia floccosa. Surfactant and high speed centrifugation studies indicate that the biosynthetic pathway involves a particulate enzyme system, possibly located on the thylakoid membranes. The following scheme, based upon identification of labeled (14)C-intermediates, is proposed for the formation of aldehydes: l-tyrosine --> 4-hydroxyphenylpyruvic acid --> 4-hydroxyphenylacetic acid --> 4-hydroxymandelic acid --> 4-hydroxybenzaldehyde --> 3-bromo-4-hydroxybenzaldehyde.