CHAPTER THREE PROTEINS
Kinesin propels organelles through the cytoplasm.
Topoisomerase untangles knotted DNA molecules.
Shape of protein is specified by its amino acid sequence.
Amino acid is linked by a covalent peptide bond.
Noncovalent bonds are individually weak but with many not
1. Van der Waals attractions: two atoms will be attracted to each other until the
distance between their nuclei is equal to their sum of van der Waals radii.
2. Hydrogen bonds
3. Electrostatic attractions: A salt crystal is very stable in vacuum, but with water it
will fall apart, because the water molecules will cover the charges.
Hydrophobic clustering force: hydrophobic molecules cluster in water. Maximizes
hydrogen bonding between molecules of water and minimizes the area of contact
between water and nonpolar molecules.
Polar amino acid side chains lie on outside
- Polar amino acids are bonded to others or to the polypeptide backbones.
- Non-polar amino acid side chains lie on inside
*(histidine often function as switches in proteins)
Proteins fold into a conformation of lowest energy.
Molecular chaperones assist in protein folding. They prevent association protein
chains.
The amyloid fibril is a long unbranched structure assembled through a repeating
aggregate of β sheets. sheets.
We show that the ability to bind to other molecules enables proteins to act as catalysts,
signal receptors, switches, motors, or tiny pumps.
Kinesin propels organelles through the cytoplasm.
Topoisomerase untangles knotted DNA molecules.
Shape of protein is specified by its amino acid sequence.
Amino acid is linked by a covalent peptide bond.
Noncovalent bonds are individually weak but with many not
1. Van der Waals attractions: two atoms will be attracted to each other until the
distance between their nuclei is equal to their sum of van der Waals radii.
2. Hydrogen bonds
3. Electrostatic attractions: A salt crystal is very stable in vacuum, but with water it
will fall apart, because the water molecules will cover the charges.
Hydrophobic clustering force: hydrophobic molecules cluster in water. Maximizes
hydrogen bonding between molecules of water and minimizes the area of contact
between water and nonpolar molecules.
Polar amino acid side chains lie on outside
- Polar amino acids are bonded to others or to the polypeptide backbones.
- Non-polar amino acid side chains lie on inside
*(histidine often function as switches in proteins)
Proteins fold into a conformation of lowest energy.
Molecular chaperones assist in protein folding. They prevent association protein
chains.
The amyloid fibril is a long unbranched structure assembled through a repeating
aggregate of β sheets. sheets.
We show that the ability to bind to other molecules enables proteins to act as catalysts,
signal receptors, switches, motors, or tiny pumps.
