Open AccessConformational Changes of Arginine Kinase Induced by Photochemical Release of Nucleotides from Caged Nucleotides
Author(s) -
Raimbault Cyrille,
Besson Françoise,
Buchet René
Publication year - 1997
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1997.00343.x
Subject(s) - nucleotide , chemistry , protonation , binding site , stereochemistry , infrared spectroscopy , adenosine diphosphate , crystallography , enzyme , substrate (aquarium) , biochemistry , biology , organic chemistry , platelet , ion , platelet aggregation , immunology , gene , ecology
The conformations of arginine kinase (AK) in AK · Mg · ADP, AK · Mg · ATP, AK · Mg · ADP · NO 3 − , AK · Mg · ADP · Arg and AK · Mg · ADP · NO 3 − . Arg complexes were investigated by measuring their reaction‐induced infrared difference spectra (RIDS). The photochemical release of ATP from ATP[Et(PhNO 2 )] and of ADP from ADP[Et(PhNO 2 )] produced distinct RIDS of AK complexes, suggesting that binding of ADP and ATP promoted different structural alterations of the enzyme active‐site. Small infrared changes in the amide‐I region were observed, indicating that about 5 – 10 amino acid residues were involved in the nucleotide‐binding site. These infrared changes were due to the structural alteration of the peptide backbone caused by the nucleotide‐binding and to the coupling effects between the nucleotide‐binding site and the other substrate (Arg or NO 3 − )‐binding site. ATP binding to AK (as well as ADP‐binding to AK in the presence of NO 3 − ) induced protonation of a carboxylate group of Asp or Glu, as evidenced by the appearance of the 1733‐cm −1 band, which was not observed with the AK · Mg · ADP, AK · Mg · ADP · Arg and AK · Mg · ADP · NO 3 − · Arg complexes. The RIDS of the AK · Mg · ADP · NO 3 · Arg complex showed new infrared bands at 1622cm −1 (negative) and at 1613 cm −1 (positive), which were not seen in the RIDS of other complexes (without NO 3 − or/and − Arg). In the transition‐state‐analog complex of AK, no protonation of the carboxylate residue (Asp or Glu) was observed, and the binding site of NO 3 − or the γ‐phosphate group of nucleotide was altered.