X-RAY MOLECULAR AND CRYSTAL-STRUCTURE OF IMIDAZOLOPYRROLOQUINOLINE, AMAIN REACTION-PRODUCT OF PYRROLOQUINOLINEQUINONE (PQQ) AND L-TRYPTOPHAN IN-VITRO

The chemical structure of imidazolopyrroloquinoline (IPQ), a main reac tion product of pyrroloquinolinequinone and L-tryptophan in vitro, has been determined by X-ray crystal analysis, The IPQ molecules exist in keto form, having three neutral carboxyl groups, and they form contin uous and prominent stacking structures in a crystal which are stabiliz ed by van der Waals, dipole-dipole and electrostatic interactions, The re are three crystallographically independent dimethyl sulfoxide solve nts in a crystal, and they stabilize the stacking layers of IPQ molecu les by intermolecular hydrogen bonds between neighboring oxygen atoms.