title: Deprotonated imidodiphosphate in AMPPNP-containing protein structures.
abstract: Many different proteins utilize the chemical energy provided by the cofactor adenosine triphosphate (ATP) for their proper function. A number of structures in the Protein Data Bank (PDB) contain adenosine 5'-(β,γ-imido)triphosphate (AMPPNP), a nonhydrolysable analog of ATP in which the bridging O atom between the two terminal phosphate groups is substituted by the imido function. Under mild conditions imides do not have acidic properties and thus the imide nitrogen should be protonated. However, an analysis of protein structures containing AMPPNP reveals that the imide group is deprotonated in certain complexes if the negative charges of the phosphate moieties in AMPPNP are in part neutralized by coordinating divalent metals or a guanidinium group of an arginine.
authors: Basic Research Program, SAIC-Frederick Inc., Argonne National Laboratory, Argonne, IL 60439, USA. dauter@anl.gov
authors: Miroslawa
authors: M
authors: Dauter
authors: Zbigniew
authors: Z
authors: Dauter
mesh_terms: D000266:Adenylyl Imidodiphosphate / Q000737:chemistry*; D004164:Diphosphonates / Q000737:chemistry*; D008958:Models, Molecular; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry*; D011522:Protons
chemical_list: D004164:Diphosphonates; D011506:Proteins; D011522:Protons; D000266:Adenylyl Imidodiphosphate; C016514:imidodiphosphonic acid