Derivatives of pesticides with an α‐amino acid function: Synthesis and effect on threonine uptake

The synthesis of several derivatives of a pesticide and an α‐amino acid are described. The process involves three steps, the last one (deprotection of the α‐amino acid group) being the most critical. The resulting products preserved their α‐amino acid group and were globally neutral. They were tested for their effect on the transport of a neutral amino acid, threonine, and two sugars, sucrose and glucose. Two derivatives markedly and specifically inhibited threonine uptake by leaf tissues of Vicia faba L. and phloem loading. Preliminary experiments suggested that the lysine‐2,4‐D derivative is a competitive inhibitor of threonine uptake. The apparent K i (0.5 mM) was much lower than the apparent K m (3 mm) of the natural substrate.