Beschreibung:
<jats:p>The polyamine synthesis enzyme spermidine synthase (SPDS) has been cloned from the model nematode <jats:italic>Caenorhabditis elegans</jats:italic>. Biochemical characterisation of the recombinantly expressed protein revealed a high degree of similarity to other eukaryotic SPDS with the exception of a low affinity towards the substrate decarboxylated <jats:italic>S</jats:italic>‐adenosylmethionine (<jats:italic>K</jats:italic>
<jats:sub>m</jats:sub>
= 110 μM) and a less pronounced feedback inhibition by the second reaction product 5’‐methylthioadenosine (IC<jats:sub>50</jats:sub>
= 430 μM). The <jats:italic>C. elegans</jats:italic> protein that carries a nematode‐specific insertion of 27 amino acids close to its N‐terminus was crystallized, leading to the first X‐ray structure of a dimeric eukaryotic SPDS.</jats:p>