Precursors of Asparagine in Lupins

Fumaric acid-1,4-¹⁴C, L-aspartic acid-4-¹⁴C, and glycine-2-¹⁴Cwere supplied for 1 to 3 h to etiolated lupin shoots that wererapidly synthesizing asparagine. The distribution of ¹⁴C inaspartate and asparagine isolated from this material was determined.With aspartic acid-4-¹⁴C adminstration radioactivity was mostlyin carbons 1 and 4 with carbon 4 having the greater amount;with fumaric acid 1,4-¹⁴C administration, radioactivity wasagain mostly in carbons 1 and 4. Aspartate labelled by fumaratecontained relatively more radioactivity in carbons 2 and 3.Little radioactivity from glycine-2-¹⁴C entered either aspartateor asparagine and this was mainly in carbon 2 and 3. It is concludedthat asparagine synthesis form aspartate is a major pathwayof asparagine biosynthesis in lupins.