Lecture 2 Reading Flashcards
What determines the folding of a protein chain?
Weak noncovalent Bonds
H bonds, electrostatic attractions, van der waals attractions. The combined strength of these bonds determines stability of folded shape.
Polypeptide backbone
Repeating sequence of atoms along the core of the polypeptide chain. Attached to repetitive chain are side chains.
Hydrophobic clustering force
Has a central role in determining shape of protein. Distribution of polar and nonpolar amino acids. Nonpolar cluster in interior.
How do most proteins fold up
Into one stable conformation that can change slightly when the protein interacts with other molecules in the cell.
Molecular chaperones
Assist in protein folding. Bind to partly folded polypeptide chains and help them progress along most energetically favorable folding pathway.
Protein domains
Structural units that fold more or less independently of each other
Common folding patterns
Alpha helix and beta sheet
Coiled coil
Stable alpha helix structure, firms when two alpha helices have most of their nonpolar side chains on one side, so they can twist around each other with three side chains facing inward
Different functions of domains
Signaling pathways
Regulation
Why do so many proteins form stable conformations
Natural selection
What makes up protein families
Each family member has an amino acid sequence and a 3d conformation that resembles those of other family members
Protein folds
Ways in proteins fold up in nature
Domain shuffling
Many large proteins have evolved through the joining of oreexsiting domains in new combinations
Protein modules
A subset of protein domains with versatile structures
Protein modules built from
Stable core structure formed from strands of beta sheets
Multi domain proteins
Have more than one domain
Binding site
Any region of a proteins surface that can interact with another molecule thorough sets of noncovalent bonds
Globular proteins
Chain folds up into ball
Fibrous proteins
Have simple, elongated three d structures