The effect of phenylserine and related compounds on the indoleacetic acid oxidase activity of cucumber hypocotyl and root extracts

Feeding of DL-threo-(3-phenylserine increases the lAA-oxidase activity of cucumber hypocotyl extracts and decreases that of root extracts. A change in the cofactor/inhibitor ratio seems to be responsible for this effect. Indirect evidence was obtained for a break-down of phenylserine into glycine and benzoic acid or derivatives thereof.