Chapter 5: Protein Function Flashcards
What are ligands?
Small organic molecules or other macromolecules that bind to a specific region of a protein (binding site) with specific orientation.
What is affinity and selectivity of a ligand-protein complex?
Affinity: how tightly the ligand binds to the protein.
Selectivity: how well the protein discriminates between structurally similar ligands.
What is the receptor protein-ligand complex?
-Binds to hormones and other signaling molecules.
- Undergo conformational change and activate signaling process within the cell.
What is the immunoglobulin protein-ligand complex?
- Antibodies (bind to antigens).
- Recognize foreign macromolecules.
What is the lectin protein-ligand complex?
- Binds to ogliosaccharides.
- Various functions, all involving the highly specific binding of particular carbohydrate groups.
What is the DNA-binding protein-ligand complex?
- Binds to DNA
- Transcription factors: bind DNA to regulate transcription of genes.
- May also bind to other ligands to regulate when they can bind to DNA.
What are transport proteins?
- Bind to various ligands.
- O2 binding proteins (myoglobin, hemoglobin)
- Membrane transporters.
What is meant by induced fit?
When ligand binding is accompanied by conformational change of protein and/or ligand to accommodate tighter binding.
What does a high Ka imply about protein-ligand interactions?
A high Ka means a high concentration of the protein-ligand complex with means there’s a high affinity (tight binding).
What is the fractional occupancy (Y)?
Y = (# of occupied binding sites) / (total # of binding sites)
What is Kd a measure of?
Affinity
What allows proteins and ligands to bind?
H-bonds, van der Waals interactions, electrostatic interactions, and the hydrophobic effect.
What are lectins?
Proteins that bind specific oligosaccharides.
What is the final electron acceptor in mitochondria during ATP synthesis?
O2
What is Heme?
Complexes metal with organic ligands to protect metal from oxidation.
