Abstract
The Mg2+ dependent asymmetry of the F1-ATPase catalytic sites leads to the differences in affinity for nucleotides and is an essential component of the binding-change mechanism. Changes in metal ligands during the catalytic cycle responsible for this asymmetry were characterized by vanadyl (VIV = O)2+, a functional surrogate for Mg2+. The 51V-hyperfine parameters derived from EPR spectra of VO2+ bound to specific sites on F1 provide a direct probe of the metal ligands. Site-directed mutations of metal ligand residues cause measurable changes in the 51V-hyperfine parameters of the bound VO2+, thereby providing a means to identification. Initial binding of the metal-nucleotide to the low-affinity catalytic site conformation results in metal coordination by hydroxyl groups from the P-loop threonine and catch-loop threonine. Upon conversion to the high-affinity conformation, carboxyl groups from the Walker homology B aspartate and MF1βE197 become ligands in lieu of the hydroxyl groups.
Original language | English (US) |
---|---|
Pages (from-to) | 539-546 |
Number of pages | 8 |
Journal | Journal of Bioenergetics and Biomembranes |
Volume | 32 |
Issue number | 5 |
DOIs | |
State | Published - 2000 |
Keywords
- F-ATPase
- FF-ATP synthase
- Vanadyl
ASJC Scopus subject areas
- Physiology
- Cell Biology