BioChem 2
1 Terms
- Catalytically perfect enzyme
- Oxyanion hole
- N-linked glycan
- PKA : Protein Kinase A which has 2 regulatory dimers and 2 catalytic dymers. It phosphorylates the substrate
- Antiporter : A secondary transporter that uses the gradient of one molecule to transform another type of molecule in the opposite direction.
The phillips mechanism for lysozyme postulates that 2 side chains play an essential role in the catalytic mechanism. In the enzyme isolated from hen egg white Glu35 and Asp52 are the 2 active side chains.
2 Problem Sets
2.1 Q1
Protein A has a binding site for ligand X with a K_d of 10^-6 M. Protein B has a binding site for ligand X with a K_d of 10^-9 M. Which protein has a higher affinity for ligand X? Explain your reasoning.
2.2 A1
Protein B has a higher affinity for ligand X compared to Protein A.
The dissociation constant ((K_d)) is inversely related to the affinity of a protein for its ligand. A lower (K_d) value indicates that the protein binds more tightly to the ligand, meaning the complex is more stable and less likely to dissociate.
- Protein A has a (K_d) of (10^{-6}) M, which means it requires a higher concentration of ligand X to achieve half-maximal binding.
- Protein B has a (K_d) of (10^{-9}) M, indicating that it can achieve half-maximal binding at a much lower ligand concentration.
Therefore, Protein B binds more tightly (with higher affinity) to ligand X than Protein A does.
