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ADP binding to TF1 and its subunits induces ultraviolet spectral changes
Journal of Biochemistry
|September 1, 1986
Summary
This study investigated adenine nucleotide binding sites on thermophilic bacterium PS3 coupling factor ATPase (TF1). Researchers identified specific high-affinity ADP binding sites on TF1
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Coupling factor ATPase (TF1) plays a crucial role in cellular energy production.
- Understanding nucleotide binding is key to elucidating TF1's catalytic mechanism.
Purpose of the Study:
- To identify and characterize adenine nucleotide binding sites on TF1.
- To determine the location and affinity of these sites, particularly for ADP.
Main Methods:
- UV spectroscopy was employed to detect conformational changes upon ADP binding.
- Equilibrium dialysis was used to quantify nucleotide binding affinities and site numbers.
Main Results:
- ADP binding induced distinct UV spectral changes in TF1, alpha, and beta subunits.
- TF1 exhibited two classes of ADP binding sites in the presence of Mg2+ (high- and low-affinity).
- The number and affinity of binding sites varied significantly in the absence of Mg2+.
Conclusions:
- Three Mg2+-dependent high-affinity ADP binding sites are located on the alpha subunit of TF1.
- A single high-affinity ADP binding site is located on a beta subunit in the absence of Mg2+.