X-ray crystallographic characterization of the Co(II)-substituted Tris-bound form of the aminopeptidase from Aeromonas proteolytica.

The X-ray crystal structure of the Co(II)-loaded form of the aminopeptidase from Aeromonas proteolytica ([CoCo(AAP)]) was solved to 2.2A resolution. [CoCo(AAP)] folds into an alpha/beta globular domain with a twisted beta-sheet hydrophobic core sandwiched between alpha-helices, identical to [ZnZn(AAP)].

Spectroscopic and X-ray crystallographic characterization of bestatin bound to the aminopeptidase from Aeromonas (Vibrio) proteolytica.

Binding of the competitive, slow-binding inhibitor bestatin ([(2S,3R)-3-amino-2-hydroxy-4-phenylbutanoy]-leucine) to the aminopeptidase from Aeromonas proteolytica (AAP) was examined by both spectroscopic and crystallographic methods. Electronic absorption spectra of the catalytically competent [Co_(AAP)], [CoCo(AAP)], and [ZnCo(AAP)] enzymes recorded in the presence of bestatin revealed that both of the divalent metal ions in AAP are involved in binding bestatin. The electron paramagnetic resonance (EPR) spectrum of the [CoCo(AAP)]-bestatin complex exhibited no observable perpendicular- or parallel-mode signal.