Final answer:
Saturation is important for ligands as it indicates the extent of receptor occupancy. Factors that affect ligand saturation include pH, temperature, other substances present, and properties of the ligands and central metal ion such as charge and the type of orbitals used. Cooperative binding in multi-site systems can also significantly influence saturation.
Step-by-step explanation:
Saturation is crucial for ligands because it determines the extent to which receptors or molecules with binding sites are occupied by these ligands. The concept of saturation can be seen in various biological and chemical contexts, such as the binding of oxygen to hemoglobin and the solubility of substances in a solution.
Several factors affect ligand saturation. In the context of hemoglobin, factors influencing oxygen-hemoglobin saturation/dissociation curve include pH levels, temperature, the presence of other gases, and the concentration of 2,3-bisphosphoglycerate in red blood cells. For the solubility of a substance in a solution, comparing the ion product (Qs) with the solubility product (Ksp) is how to determine if a solution is saturated. When Qs equals Ksp, the solution is at saturation.
For metal-ligand complexes, the crystal field splitting affects saturation as well. It depends on the properties of the ligands and the metal, such as the charge on the metal ion and whether it's using 3d, 4d, or 5d orbitals. Different ligands produce different degrees of crystal field splitting, affecting the ligand-binding affinity.
Furthermore, ligand-binding systems with multiple binding sites, such as hemoglobin, show cooperative binding. The binding of one ligand can affect the affinity of the molecule for additional ligands, leading to a characteristic sigmoidal saturation curve where, at very high or low percent saturation, affinity for the ligand can change dramatically.