Synthesis of 3‐arsonoalanine and its action on aspartate aminotransferase and aspartate ammonia‐lyase: Comparison with arsenical analogues of malate and fumarate

dl‐3‐Arsonoalanine has been synthesized by the Strecker synthesis from the unstable compound arsonoacetaldehyde. It inactivates pig heart cytosolic aspartate aminotransferase and inhibits aspartate ammonia‐lyase by competing with aspartate (K_i/K_m 0.23). The fumarate analogue (E)‐3‐arsonoacrylic acid and the malate analogue (RS)‐3‐arsonolactate also inhibit fumarate hydratase, competing with fumarate (K_i/K_m 1.8) and malate (K_i/K_m 1.6) respectively. Attempted non‐enzymic transamination of 3‐arsonoalanine gave elimination of arsenite, in contrast with the transamination of 3‐phosphonoalanine, which is either successful or leads to loss of phosphate.