If the compounds bind the immobilized protein, the binding of the second protein will be reduced; otherwise, the binding will be largely retained.
This suggests that when one of the two domains in each monomer binds the PhC head group of the bull spermatozoa membrane phospholipids, binding of the second domain to a neighboring PhC head group is likely to involve reorientation of the second domains relative to the first one, such that the two domains end up pointing in the same direction, in a parallel configuration.
When the ATP concentration is saturating, the binding of α-ketoglutarate displays strong anticooperativity, such that the first molecule binds with a Kd in the low micromolar range and the binding of the second and third molecules occurs with a Kd ∼1−2 orders of magnitude higher (5, 6).
The binding of the second K+ ion also started with water dehydration at about 159 ns (Fig. 2D).
The authors conclude a subsite binding of the second peptide unit close to the main binding pocket.
Substrate activation can result from an allosteric effect due to binding of the second substrate molecule on the PAS.
Mulliken population analysis has shown that it is only the redistribution of charges between K atom and H2 molecules which is responsible for binding of the second H2 molecule.
In this system, the binding of the first guest (1 2 saccharide/boronic acid complex) suppresses the rotational freedom of the two porphyrin planes, which facilitates the binding of the second guest.
The results show that binding of dcAdoMet to pfSPDS stabilizes the conformation of the flexible gatekeeper loop of the enzyme and affects the conformation of the active-site amino acid residues, preparing the protein for binding of the second substrate.
While the top area became increased by about 0.04 nm2 due to the upward shift of the first K+ ion pushed by electrostatic repulsion from the second K+ ion, the bottom G-tetrad gate area decreased significantly by the binding of the second K+ ion through bottom pathway.
