# Crystal structure of putrescine aspartic acid complex

Ramaswamy, S and Murthy, MRN (1990) Crystal structure of putrescine aspartic acid complex. In: Current Science, 59 (7). pp. 379-382.

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Polyamines, putrescine, spermidine and spermine are ubiquitous biogenic cations believed to be important for a variety of cellular processes. In order to obtain structural information on the interaction of these amines with other biomolecules, the structure of a complex of putrescine with aspartic acid was determined using single crystal X-ray diffraction methods. The crystals belong monoclinic space group $C_2$ with $a = 21.504 \AA$, $b = 4.779 \AA$, $c = 8.350 \AA$ and $\beta = {97.63}^{\circ}$. The structure was refined to an R factor of 8.4% for 664 reflections. The asymmetric unit contains one aspartic acid and half putrescine molecule. The conformation of aspartic acid corresponds to its most favorable extended structure. The putrescine molecule, although on a 2-fold special position, lacks 2-fold symmetry. The putrescine backbone has a transgauche conformation. The energy required for distorting the putrescine molecule from its most favourable zigzag structure is presumably derived from both hydrogen bonding and electrostatic interactions.